Top 17 Keensert® Questions: Expert Answers to Common Questions (Part 2)

Top 17 Keenserts® Frequently Asked Questions Answered by MF Supply -Part 2

In this second part of our three-part series, Top 17 Keensert® Frequently Asked Questions, we dive deeper into selecting the ideal key-locking inserts (a.k.a. Keenserts®) for your specific application. We’ll cover available insert materials—ranging from stainless steel and carbon steel to specialty alloys like 4140—and explain key sizing and thread-fit considerations. You’ll discover why key-locking inserts feature slightly oversized OD, and whether different lengths are available for various sizes. We will also share a simple visual trick that makes it easy to distinguish between self-locking and non-self-locking Keenserts®. Finally, we’ll offer practical advice for choosing the right key-locking insert material for your projects.


8. In what materials are key-locking inserts available off-the-shelf?

Key-locking inserts are commonly available off the shelf in carbon steel (black-phosphate steel) and 303 stainless steel. Additional materials include A4140, A286, and Nitronic 60, which may require a lead time and/or a minimum order.

Note: All sizes may not be available in all materials.

9. Do key-locking inserts come in different lengths?

Yes, key-locking inserts come in different lengths to accommodate various application requirements. The length of each key-locking insert is preset and is a function of the insert’s internal and external diameter. This ratio is usually determined by the manufacturer and can vary based on the thread size, material thickness, and the desired strength of the threaded connection.

Note: When selecting a key-locking insert, the length is usually chosen based on the thickness of the parent material and the load requirements. Thinwall key-locking inserts are often shorter, while heavy-duty or solid inserts may be longer to provide greater thread engagement and strength.

10. Why are the measurements of the outer diameters of Keensert® style key-locking inserts slightly larger than the standard UNC or UNF thread tolerances?

The outer diameter of key-locking inserts is slightly larger to ensure a tight fit and sufficient thread engagement in the parent material, compensating for tapped hole variations.

11. Why are self-locking Keenserts® a darker color than non-self-locking Keenserts®?

Self-locking Keenserts® are often treated with a dry-film lubricant that makes them easier to install and can result in a darker appearance compared to non-self-locking types.

12. How do I select the correct key-locking inserts material for my application?

The material choice for a key-locking insert depends on the application’s requirements, such as strength, corrosion resistance, temperature tolerance, parent material and environment. Generally speaking, 303 and Nitronic 60 stainless steel are more common for harsh environments, and carbon steel (i.e., black-phosphate steel) is used for general applications. We recommend reaching out to us or consulting a fastener engineer as a best practice.


Stay tuned for the next and final installment in this series, where we’ll cover advanced topics including how Keenserts® style key-locking inserts stack up against alternative threaded inserts, such as helical inserts (AKA HeliCoil®), and clarify common misconceptions.

Remember, expert advice is just a click away. If you have any questions, feel free to connect with our team or send us a request for quote and our team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!


Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


MF Supply Work With Us

Your Purchasing Department’s Secret Weapon!
Here are 5 reasons to buy from MF Supply

  • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
  • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
  • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
  • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
  • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

Logos of various certifications and associations, including WBE, II Thomas Verified Supplier, DPA Industrial, SBA WOSB, and MFDA.
MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


Top 17 Keensert® Questions: Expert Answers to Common Questions (Part 1)

Top 17 Keenserts Frequently Asked Questions Answered by MF Supply

Navigating the world of key-locking inserts—Keenserts®—doesn’t have to be complicated. Our comprehensive guide with 17 frequently asked questions cuts through the confusion, addressing the top issues related to selecting, shopping for and installing key locking inserts. In this first installment of our 3 part series, we’ll cover the first 7 questions which focus on the fundamentals, including the differences between self-locking and standard inserts, installation essentials, and common questions when drilling and tapping the holes in the parent material.  


1 – What is the difference between a key locking and a self-locking Keensert®?

key locking threaded insert, also known by its trademarked name Keensert®, is a solid bushing style insert with both internal and external threads. It has wedges or “keys” on one end that lock it into place after installation, preventing loosening due to vibration. All Keenserts® are key-locking inserts. Key-locking inserts come in self-locking and non-self-locking styles (sometimes referred to as free-running). Self-locking style key-locking inserts have a distorted internal thread that creates a mechanical lock, making them some of the strongest inserts available. This mechanical self-locking feature is stronger than adhesive-based chemical thread-lockers.

2 – What tools do I need to install a key-locking insert?

To properly install a key-locking insert, AKA Keensert®, you will need the following tools:

  • Drill: to make a hole in the parent material.
  • Tap: To tap threads that will accept the external thread of the insert.
  • Keensert® Installation Tool & Hammer: to drive the keys into the parent material.

Depending upon your application, you may also require a countersink tool and a broaching tool. Note: If you have a few hundred inserts to install, the manual process detailed above works fine. However, if you are installing these Keenserts® by the thousands, then you will want to use a pneumatic power tool to speed up the processes.

3 – How do I install key-locking Inserts?

To manually install a key-locking insert it requires a 4-step process:

  1. Drill a hole and countersink the parent material. Note: The drill size is specific to the Keensert® you are installing.
  2. Tap threads into the parent material according to the insert’s external thread, pitch and tolerance.
  3. Manually screw the key-locking insert into the tapped hole.
  4. Place the installation tool on top of the insert. Strike with a hammer to drive down the locking keys creating a mechanical lock.

4 – What is a broaching tool and when will I need one?

A broaching tool is an extra installation tool that is used in hard material. Parent materials harder than RC30, such as A286, A4140 or anodized aluminum may require the tapped holes be broached prior to installing the key-locking insert. The broaching tool has blades that create slots so the keys can be driven into the parent material.

5 – Where do I find the drill size to install a key-locking insert?

The drill size for a key-locking insert is typically found in the product specifications or installation guide provided by the manufacturer.

Note: The outer diameter of Keenserts® are slightly larger than the standard drill hole to ensure a tight fit and sufficient thread engagement in the base material, compensating for tapped hole variations.

6 – Where do I find the tap size to install a key-locking insert?

The tap size for a key-locking insert is typically found in the product specifications or installation guide provided by the manufacturer. The tap will typically match the size, pitch and tolerance of the insert’s external diameter and thread.

7 – How do I find the correct tool to install my Keensert®?

The correct installation tool is usually specified by the Keensert® manufacturer and can be found in the product’s documentation or on the manufacturer’s website. Installation tools are specific to the external and internal diameter of each unique insert part number. Note: Some tools work for multiple sizes.


Stay tuned for the next installment in this series, where we’ll dive into frequently asked questions about Keensert® measurement differences, material selection options, and more!

In the meantime, if you have any questions, feel free to Connect with our team or send us a request for quote and our team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!


Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


MF Supply Work With Us

Your Purchasing Department’s Secret Weapon!
Here are 5 reasons to buy from MF Supply

  • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
  • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
  • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
  • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
  • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


MF Supply Is Now an Authorized Nord-Lock® Distributor!

MF Supply, a leading New Jersey-based WBE/SBE certified distributor and fastener sourcing expert, is thrilled to announce a significant expansion of our product line through a new partnership with Nord-Lock®, making us an authorized distributor. This expansion complements our vast range of commercial, mil-spec, domestic, and OEM branded fasteners, aligning with our commitment to meeting the evolving needs of the precision manufacturing industry.

Explore Nord-Lock’s Advanced Bolting Solutions

With over 35 years of expertise, Nord-Lock specializes in washers that ensure bolted joints remain secure under challenging conditions. Their innovative products range, available for RFQ directly on our website, includes:

  • Wedge-Lock Washers: These are crafted to effectively secure bolted joints using tension, ideal for heavy machinery and transportation sectors.
  • X-Series Washers: Combining wedge-locking with a spring effect, these washers address issues like thermal cycling and dynamic loads.
  • Superbolt Tensioners: Simplify the tightening of large bolts, enhancing both efficiency and safety during installations.
  • SC-Washers: Designed specifically for structural steel applications, they ensure optimal load distribution and are compliant with European standards.

MF Supply Expanding to Meet Industry Demands

This partnership with Nord-Lock adds to our recent catalog update, which now features over 43,928 unique items, including threaded and helical inserts, specialty bolts, socket cap screws, Acme, Captive, EZ-Lok and Holo-Krome branded products. Our expansion into Nord-Lock products supports industries such as aerospace, energy, and manufacturing, providing our clients with top-tier, reliable fastening solutions.

By bolstering our product offering in these key areas, we aim to be the preferred supplier for manufacturers in various sectors, including: aerospace, OEMS of instrumentation, equipment and machines, architectural metal and glass, sheet metal fabrication, contract manufacturers, lighting, furniture, and elevators.

Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Manufacturers eager to explore our product catalog, including our recently expanded product categories, are encouraged to visit our website at www.mfsupply.com, reach out to us at sales@mfsupply.com or request a quote. Our MF Supply team of sourcing experts will help find what you need. “Finding the right screw for you” is our tag line after all!


Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


MF Supply Work With Us

Your Purchasing Department’s Secret Weapon!
Here are 5 reasons to buy from MF Supply

  • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
  • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
  • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
  • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
  • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


MF Supply Recertified as a Small Woman-Owned Business Enterprise!

MF Supply, a leading distributor of fasteners and hardware, is proud to announce that we have successfully been recertified as a Women’s Business Enterprise (WBE) and Small Business Enterprise (SBE) by the state of New Jersey. This certification reaffirms MF Supply’s commitment to providing high-quality products while fostering diversity and inclusion in the manufacturing and distribution sectors.

      How Does This Benefits You

      • Meet Your Diversity Goals: As a certified WBE and SBE supplier, we can help your business fulfill inclusion and diversity requirements while ensuring top-tier service and reliability.
      • Hard-to-Find Parts? Solved! From mil-spec fasteners to custom hardware, we specialize in sourcing hard-to-find components like Keensert® style key-locking inserts, helical inserts, dowel pins, socket head cap screws and more—all with precision and speed.
      • Decades of Expertise: Partner with a team that understands your needs. Whether it’s aerospace engineering, manufacturing, or government projects, we act as an extension of your purchasing departments providing lightning-fast responses, direct support, and competitive pricing.

      Why Choose MF Supply?

      With 50 years of fastener experience, we offer lightning-fast responses, direct phone support, free samples, and act as an extension of your team. We are fastener & sourcing experts, so you don’t have to be. With vast experience as a leading supplier and distributor of commercial and Mil-Spec fasteners, both in inch and metric sizes, we excel in providing:

      Featured Products:

      Some of our featured product lines include:

      1. Keensert® Style Key-Locking Inserts
      2. Helical Inserts (aka HeliCoil®)
      3. Precision Dowel Pins
      4. Precision Shoulder Screws
      5. Socket Head Cap Screws
      6. Other Socket Products
      7. Standoffs & Spacers
      8. Mil-Spec Fasteners
      9. Custom-made and reworked hardware and components

      Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Visit our website, Connect with our team or send us a request for quote and our team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!


      Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


      MF Supply Work With Us

      Your Purchasing Department’s Secret Weapon!
      Here are 5 reasons to buy from MF Supply

      • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
      • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
      • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
      • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
      • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

      MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


      Mil-Spec Fasteners in Stock at MF Supply

      Are you searching for certified Mil-Spec fasteners to meet your bill of requirements (BOM) or project specifications? Look no further! MF Supply specializes in sourcing and supplying domestically manufactured AN, MS, and NAS Mil-Spec fasteners for aerospace, defense, and industrial applications. MF Supply stocks over 3,000 unique certified parts from the Qualified Suppliers List for Manufacturers & Distributors (QSLM & QSLD). Mil-Spec products stocked include Keensert® Style Key-Locking Inserts, Helical (HeliCoil®) Inserts, Precision Dowel Pins, Slotted Spring Pins, Extended Prong Cotter Pins, Nuts, Washers, Machine Screws, Precision Shoulder Screws, Hex Head Cap Screws/Bolts, Socket Head Cap Screws, Set Screws, Self-Tapping Screws and more. All Mil-Spec parts undergo rigorous testing and are DFARS or domestically manufactured with Certificate of Conformance (COC) and Material and Physical certification paperwork available to ensure compliance.

      Buy Mil-Spec Fasteners and Precision Electronic Hardware at MF Supply!

      We Have All the Mil-Spec Fasteners and Precision Hardware You Need

      We offer a huge selection of DFARS certified and domestic Mil-Spec fasteners directly on our website, making it easier for you to find exactly what you need for your project at the click of a button or via RFQ depending on your preferred method of procurement. Below is a list of some of our most popular Mil-Spec product categories available:

      1 – Mil-Spec Keensert® Style Key-Locking Inserts

      • Standards: MS51830, MS51831, MS51832, NA0146, NA0147, NA0148, NA0149, NA0150, NA0151, and NAS1395.
      • Styles: Miniature, Thin Wall, Heavy Duty, Thick Wall, and Extra Heavy Duty
      • Available Sizes: 2-56 to 1/2-13 Internal thread for inch sizes and M2 x 0.4 to M24 x 2 for metric sizes
      • Materials: 4140 alloy steel, Nitronic 60, CRES A286 and 303 series stainless steel
      • Applications: Can be used to create new threads, for thread reinforcement, and to repair stripped threads

      2 – Helical Inserts (aka HeliCoil®)

      • Standards: MS121, MS122, MS124, MS21209, MA3279, and MA3329
      • Styles: Free-running and self-locking
      • Available Sizes: #2-56 to 1½-6 for inch sizes and M2 to M36 for metric sizes
      • Materials: CRES 300/18-8 stainless steel
      • Applications: Can also be used to create new threads, for thread reinforcement, to convert threads between inch and metric sizes, and to repair stripped threads

      3 – Mil-Spec Precision Dowel Pins

      • Standards: MS16555, MS16556, and MIL-P-21143
      • Styles: Interference/Press Fit, Undersize/Slip Fit and Oversize +.001
      • Sizes: Diameters from 1/32 to 1 inch and lengths from 3/32 to 6 inches
      • Materials: CRES 303, 400, 416 series stainless steel
      • Applications: Can be used as a hinge, shaft, precise location device or pivot to align or secure parts within a precision assembly or fixture

      4 – Mil-Spec Slotted Spring Pins

      • Standards: MS16562
      • Styles: Slotted
      • Sizes: Diameters from 1/16 to ½ inch and lengths from 3/16 up to 3 inches long
      • Materials: Alloy steel with a zinc phosphate finish
      • Applications: Can be used as a hinge or shaft for the purpose of securing and fastening components together

      5 – Mil-Spec Extended Prong Cotter Pins

      • Standards: MS9245
      • Styles: Extended Prong
      • Sizes: Diameters from 1/32 to 5/32 inch and lengths from 1/4 to 1/2 inches long
      • Materials: T321 stainless steel
      • Applications: Designed to retain/secure a variety of fasteners such as bolts, nuts and pins in place and prevent them from sliding or coming out

      6 – Mil-Spec Hex Finished Nuts

      • Standards: MS51967B & MS51967C
      • Styles: Grades B & C
      • Sizes: Stock sizes from 1/4-20 through 3/4-10 inches thread
      • Materials: Alloy steel with a cadmium yellow finish
      • Applications: Used to fasten parts together by pairing and tightly securing bolts in place

      7 – Mil-Spec Hex Machine Nuts

      • Standards: MS35649 & MS35650
      • Available Sizes: Stock sizes from 2-56 through 3/8 thread
      • Materials: Alloy steel cadmium yellow and 300/18-8 series stainless steel
      • Applications: Typically paired with bolts or screws to ensure parts/components stay firmly fastened in place

      8 – Mil-Spec Washers

      • Standards: MS51848, NAS620, MS35333, MS35335, MS35338, AN960, AN960-C, AN970, MS15795, MS27183, NAS1149 & NAS620
      • Styles: flat, light flat, flat machine screw, split lock, high collar split lock, internal tooth lock, and external tooth lock
      • Materials: Carbon steel, Alloy steel and 300/18-8, 316, 400 series stainless steel
      • Applications: Distribute the load of a fastener, such as a bolt or screw, over a larger surface area. This in turn helps reduce the effects of wear, damage or vibration on the fastener assembly by providing a cushion between the fastener head and the parent material

      9 – Mil-Spec Machine Screws

      • Standards: MS24693, MS35190, MS35191, MS35206, MS35207, MS35265, MS35266, MS35275, MS35276, MS51957, MS51958, MS51959, & MS51960
      • Styles: 82d & 100d Flat Phillips, Drilled Slotted Fillister, Philips Pan Head
      • Available Sizes: Diameters range from 0-80 to 3/8-16 inches with lengths ranging from 3/32 to 3 inches long
      • Materials: Carbon steel, Alloy steel, and 300/18-8 series stainless steel
      • Applications: Often used in conjunction with other fastening elements, such as washers and nuts, they have uniform threads that when fastened engage with corresponding threads in a tapped hole or nut, creating a secure mechanical connection between components

      10 – Mil-Spec Precision Shoulder Screws

      • Standards: MS51576 & MS51575
      • Styles: Hex and slotted drives
      • Available Sizes: Stock sizes range from 4-40 to 3/8-16 thread
      • Materials: 300/18-8 series stainless steel
      • Applications: Feature a cylindrical unthreaded shoulder that serves as a dowel or pivot point for rotating parts, also used to hold parts together within a precision assembly

      11 – Mil-Spec Hex Head Cap Screws/Bolts

      • Style: Hex head
      • Standards: MS35307, MS35308, MS90725, MS90726, MS90728G & MS90727F, B1821
      • Sizes: Stock sizes range from 1/4-20 through 1-1/4 diameter
      • Materials: Alloy steel, 300/18-8 Series Stainless Steel
      • Applications: Their hexagonal heads allow for the application of high torque using a wrench or socket, which enables a very tight and secure fastening for load-bearing structures in military vehicles, aircrafts and more

      12 – Socket Head Cap Screws

      • Style: Socket head
      • Standards: NAS1352C / MS16995, NAS1351C / MS16996, MS16997, MS16998, NAS1351N & NAS1352N, & MS24671
      • Sizes: Stock sizes range from 0-80 through 1-1/2 diameter
      • Materials: Alloy steel, 300/18-8 series stainless steel, A286
      • Applications: These screws have a cylindrical head with a hexagonal recess (socket) that allows for tightening with an Allen wrench/hex key. The socket head design allows for use in applications where there is limited space. The hexagonal socket allows for precise control during assembly, ensuring the screw is driven straight and accurately into the desired position

      Can’t find what you’re looking for in the list above? Send us an RFQ with the product description or part number that you are looking for and our MF Supply team of sourcing experts will help find what you need!

      Why Buy Mil-Spec Fasteners from MF Supply?

      When precision, compliance, and reliability are non-negotiable, MF Supply stands out as a trusted partner for mil-spec fasteners. Here’s why industrial buyers across aerospace, robotics, defense, and manufacturing sectors turn to MF Supply:

      Compliance and Certification: MF Supply’s mil-spec fasteners meet stringent U.S. Department of Defense (DoD) specifications, including MS51830, MS51831, and more. Each fastener is available with Material and Physical Test Reports, Certificates of Conformance, and DFARS/Domestic Statements—providing peace of mind for critical applications.

      Sourcing Expertise: MF Supply works with the best factories across fastener categories, offering tailored solutions based on your budget, delivery and certification needs.

      Reliability Across Critical Industries: Serving aerospace, defense, robotics, automotive, and manufacturing sectors for over 50 years, MF Supply is a trusted partner for industries where delivery times, precision and reliability are non-negotiable.

      Shop Over 3,000 Unique Mil-Spec Fasteners and Precision Hardware Directly on Our Website!

      Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Manufacturers eager to explore our Mil-Spec products’ catalog, including our other recently expanded product categories, are encouraged to visit our website at www.mfsupply.com, reach out to us at sales@mfsupply.com or request a quote. Our MF Supply team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!


      Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


      MF Supply Work With Us

      Your Purchasing Department’s Secret Weapon!
      Here are 5 reasons to buy from MF Supply

      • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
      • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
      • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
      • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
      • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

      MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


      Case Study: Solving Precision & Compliance Challenges for a Leading U.S. Biomedical Manufacturer with Custom Made Dowel Pin Solution

      A prominent U.S.-based biomedical company faced a significant challenge. They required custom stainless steel dowel pins for a new medical device, with the following critical specifications: 

      • Non-standard size: 1/2″ in length, with an unusual diameter of .085″. 
      • Tight tolerances: +/- .0005″ for both the diameter and length. 
      • Limited quantity and budget: A few thousand pieces, with a total budget under $2,500. 
      • Full documentation: Required full material certification, manufacturer’s lab test report, heat treat certifications, and a signed MFG Certificate of Conformance. 

      The company’s existing supply chain was unable to meet these specific requirements. After weeks of searching, they found no U.S. manufacturer that could provide the high-precision parts, full paperwork compliance, and stay within their budget or delivery timeline. 

      MF Supply stepped in, offering a tailored solution that addressed every aspect of the customer’s needs: 

      • Fast and Flexible Quoting: Within 48 hours, MF Supply provided a detailed quote with multiple quantity price breaks and an optional expedite fee for faster delivery. 
      • Made in the USA: MF Supply partners exclusively with domestic U.S. factories capable of producing parts to exacting standards and precise tolerances. 
      • Full Traceability and Compliance: We ensured all required certifications were included, such as material certifications, lab test reports, heat treatment certifications, and a signed Certificate of Conformance. This level of documentation allowed the biomedical company to maintain their high compliance standards. 
      • Efficient Delivery: MF Supply expedited the manufacturing process, and the parts were delivered within 8 weeks from the receipt of the order—well within the customer’s timeline. 

      By partnering with MF Supply, the biomedical company was able to: 

      • Receive their custom-made, USA-manufactured stainless steel dowel pins with exact specifications, without compromising on quality or documentation. 
      • Stay within budget, ensuring they did not exceed their $2,500 limit for the project. 
      • Ensure full compliance with all regulatory and internal quality control requirements, thanks to the comprehensive documentation provided with the parts. 
      • Meet tight deadlines, with expedited manufacturing and an on-time delivery schedule. 

      The success of this project has led to repeat orders, and MF Supply now maintains safety stock for this customer, ensuring they can meet future urgent requests without any production delays. 

      For manufacturers who need domestically certified, precision dowel pins or other custom parts with exacting tolerances, short lead times, and full traceability from ISO-certified U.S. factories, MF Supply is the partner of choice. Our ability to provide complete, certified paperwork and fast delivery helps manufacturers avoid costly delays and ensure compliance—every time. 

      Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Visit our website at www.mfsupply.com, reach out to us at sales@mfsupply.com or request a quote. Our MF Supply team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!


      Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


      MF Supply Work With Us

      Your Purchasing Department’s Secret Weapon!
      Here are 5 reasons to buy from MF Supply

      • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
      • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
      • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
      • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
      • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

      MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


      Shop E-Z LOK Threaded Inserts, Installation Tools & Thread Repair Kits at MF Supply

      Are you a precision engineer or industrial manufacturer looking for reliable threaded inserts and installation solutions? Look no further! MF Supply is an authorized E-Z LOK distributor, and we are proud to offer the complete range of over 1,300 unique E-Z LOK products, providing high-quality threaded inserts, installation tools, and thread repair kits to meet your most demanding project requirements. Whether you are in the automotive industry, aerospace, or heavy manufacturing, E-Z LOK solutions are designed to improve efficiency and ensure the durability of your project.

      Buy E-Z LOK Threaded Inserts, Installation Tools, and Kits at MF Supply!

      Why Choose E-Z LOK Products?

      As a precision engineer or industrial manufacturer, you know that quality, durability, and ease of installation are critical factors for maintaining optimal performance.

      E-Z LOK is a trusted brand name in threaded insert solutions across a wide range of industries. Their products are engineered to meet rigorous quality standards such as TSCA PBT, RoHS, REACH, DFARS, and ITAR, ensuring excellent performance in the most demanding applications. If you need to repair stripped threads or create reliable, wear-resistant threads in materials like wood, plastic, or metals, E-Z LOK threaded inserts, installation tools & thread repair kits provide all the solutions you need! E-Z LOK products provide:

      • Thread repair and reinforcement in metals, woods, and plastics.
      • Durable holding power in materials that are too soft or thin to hold threads on their own, or in materials with unthreaded, damaged or stripped holes.
      • Versatility in their range of threaded insert designs, including thin wall, standard wall, extra heavy wall, screw-locking, and automotive options.
      • Corrosion-resistant materials, such as Brass and 303 & 316 Series Stainless Steel for long-lasting performance in harsh environments.
      • Easy installation with or without specialized tools and kits, reducing downtime and extra costs.

      The Complete Range of E-Z LOK Products at Your Finger Tips

      We offer the complete selection of E-Z LOK products directly on our website, making it easier for you to find exactly what you need for you project at your fingertips. Below is an overview of the E-Z LOK product categories available.

      Threaded inserts are crucial components used to add strong, durable threads in softer materials or to repair damaged threads in existing assemblies. If you’re working with metal, wood, or plastic, E-Z LOK threaded inserts offer the perfect solution for reinforcing threads; repairing stripped or damaged threads without re-machining the entire part; and ensuring long-lasting, wear-resistant connections in high-stress applications. These threaded inserts are available in thread sizes ranging from 0-80 through 1-1/2-12 for inch/imperial sizes, and M2 x 0.4 through M39 x 4 for metric thread sizes. Materials offered include Aluminum, Brass, Carbon Steel, 303 & 316 Series Stainless Steel, and Zinc.

      • E-Z Coil™ Threaded Inserts: Designed for repairing damaged threads or creating new threads in softer materials like aluminum and magnesium. Made from high-quality Carbon Steel, Stainless Steel, and Zinc, they provide strong, permanent threads.
      • E-Z Fin™ Threaded Inserts: Ideal for applications in plastics and soft metals, ensuring secure fastening and vibration resistance. Available in Brass and Stainless Steel.
      • E-Z Hex™ Threaded Inserts: Perfect for applications requiring frequent disassembly and reassembly, these inserts offer a secure fit and easy handling due to their hexagonal shape, which prevents rotation.
      • E-Z Knife™ Threaded Inserts: Suitable for hard woods and thermoset plastics, providing high pull-out strength and vibration resistance with a knurled exterior for superior grip.
      • E-Z Press™ Threaded Inserts: Designed for plastics and soft metals, these press-fit inserts offer high pull-out resistance without the need for thread tapping.
      • E-Z LOK™ Threaded Inserts: Versatile inserts for various materials, offering strong threads in Brass, Carbon Steel, Stainless Steel, and Zinc.
      • E-Z Sonic™ Threaded Inserts: Used in applications requiring ultrasonic or heat installation in thermoplastics, ensuring a secure fit.

      One of the major benefits of E-Z LOK threaded inserts is that they are designed for easy installation. Most inserts can be installed without the need for specialized tools, but for high-precision or high-volume projects, having the right tools can be the difference between meeting or failing a deadline. Hence, the comprehensive list of E-Z LOK installation tools, which are engineered to meet ASME and ANSI industry standards, ensure that you get the job done with precision and quickly. Installation tools available include:

      • E-Z Coil™ Installation Tool: Ensures proper insertion and secure fit of E-Z Coil™ Threaded Inserts, which are available in various sizes.
      • E-Z LOK™ Drills (Brad Point HSS, Reduced Shank, HSS): Used for precise drilling in wood, plastic, and metal, ensuring clean and accurate holes for insert installation.
      • E-Z LOK™ Threaded Insert Drive Tools: Designed for driving inserts into pre-drilled holes, ensuring proper alignment and secure fit.
      • E-Z Coil™ Extract Tool & Tang Break Off Tool: Facilitates easy removal and clean installation of E-Z Coil™ Threaded Inserts.
      • E-Z LOK™ Taps (HSS Standard Bottoming, Standard Bottoming, HSS STI Bottoming): Used for creating accurate and durable threads in various materials, specifically for E-Z Coil™ inserts.

      E-Z LOK thread repair kits offer a fast, cost-effective solution. These kits include all the necessary components for quick, reliable thread repairs in metals, plastics, and wood, ensuring minimal downtime, maximum efficiency, and long-lasting durability in high-stress environments. With E-Z LOK’s reputation for quality and ease of use, these kits help maintain equipment performance and extend service life. Available kits include:

      • E-Z LOK™ Coil Thread Repair Kit: Comprehensive kit for repairing damaged threads in metals, including inserts, drills, taps, and installation tools.
      • E-Z Hex™, E-Z Knife™ Threaded Insert Installation Kits: Ensure secure installation with all necessary tools and inserts.
      • E-Z LOK™ Thread Repair Kit: Versatile kit for general-purpose thread repair, offering a range of tools and inserts.
      • E-Z LOK™ Threaded Insert Assortment Kit: Provides a variety of inserts and tools for multiple applications.
      • E-Z LOK™ Solid Wall Thread Repair Kit: Ensures strong and durable threads in high-stress applications.
      • E-Z Sonic™ Threaded Insert Assortment Kit: Comprehensive kit for ultrasonic and heat installation in thermoplastics, providing secure and reliable threads.

      Why Buy E-Z LOK Thread Inserts, Tools & Kits from MF Supply?

      MF Supply is a leading supplier of threaded inserts including E-Z LOK threaded inserts, Keensert® style key-locking inserts and helical wire inserts. We stock and source a huge inventory, including major OEM brands and equivalents to HeliCoil®, Recoil®, KATO®, PowerCoil, Bollhoff, Perma-Coil, V-Coil, Time-Sert and more — in inch/imperial, metric and Mil-Spec sizes and materials. Our Mil-Spec products are DFAR compliant with COC and full certifications available upon request.

      Shop the complete catalog of E-Z LOK products directly on our website!

      Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Manufacturers eager to explore our product catalog, including our recently expanded product categories, are encouraged to visit our website at www.mfsupply.com, reach out to us at sales@mfsupply.com or request a quote. Our MF Supply team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!


      Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


      MF Supply Work With Us

      Your Purchasing Department’s Secret Weapon!
      Here are 5 reasons to buy from MF Supply

      • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
      • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
      • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
      • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
      • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

      MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


      Ultimate Guide: Inch, Metric, and Mil-Spec Precision Shoulder Screws Cross Reference Charts and Guide

      At MF Supply, we spend a lot of time sourcing hard to find, back ordered, expensive, or out-of-stock OEM hardware brands. We do this in order to save money and to reduce long lead times for our customers, without sacrificing quality. One of our core competencies is crossing brand names to functionally equivalent parts that maybe Mil-spec, alternative brands or generic parts.

      What Is a Functional Equivalent Fastener?

      In the fastener industry, a functional equivalent fastener is a component/part that matches a brand-name product in form, fit, and function, including material and plating specifications, but is produced by a different manufacturer. As a result, the industrial marketplace features a myriad of fasteners and components that are registered under various trademark brands, but that offer the same functionality. This, in turn, allows you to achieve the same product performance and quality desired at a potential lower cost and with shorter lead times than you would get with fasteners from well know or expensive brands.

      Does My OEM Brand Have A Functional Equivalent or Alternative Fastener?

      Many OEM brands available in the industry today have generic functional equivalents or alternatives. Below is a comprehensive list of popular brand names that show up quite often in the fasteners space and that have generic equivalent or alternative options to their OEM branded products:

      3 Star Rivets USA, ABBATRON®, ALCOA, AMATOM®, APEX®, ARCONIC®, ATLAS®, AVDEL®, AVK®, B. F. GOODRICH, BOLLHOFF, BUCKEYE, CAPTIVE, CELUS®, CHERRY®, CONCORD, FASTENAL, GESIPA®, GLOBE ELECTRONICS, GRIPCO®, H. H. SMITH, HELICOIL®, HOWMET, HUCK, INDUX, INTERFAST, KATO®, KEENSERT®, KEYSTONE, LOCTITE®, LYN-TRON, MACLEAN­ ESNA®, MARSON®, MCMASTER-CARR, MISUMI, MSC INDUSTRIAL, PEM®, PIC DESIGN®, POP®, POWERS®, QUICKSCREWS, RAF, RECOIL®, RED HEAD®, ROTOR CLIP®, SHEREX, SIMPSON, SOUTHCO®, SPS TECHNOLOGIES, TINNERMAN®, U. S. ANCHOR, UNICORP, VIP, W. M. BERG, W. W. GRAINGER, WALDES TRUARC®.

      Do Precision Shoulder Screws Have Functional Equivalents?

      Yes! Precisions shoulder screws, also known in the industry as just shoulder screws or tight tolerance shoulder screws, do have functional equivalents. In fact, one surefire way to save money and shorten delivery time is to cross the OEM branded precision shoulder screw on your bill of materials to a functional equivalent.

      Popular brands in the precision shoulder screws space include: Amatom, Cambion, Concord, Globe, HH Smith, Keystone, Lyn-tron, Misumi, Pic Design, RAF, and WM Berg. A comprehensive selection of Precision Shoulder Screws is also offered by McMaster-Carr, MSC, and Grainger.

      Let’s take, for example, the following inch/imperial sized precision shoulder screw: 3/16” shoulder diameter x 1” long x 8-32 thread in SS18-8 (300 Series) with a hex-socket drive. This shoulder screw is offered by the seven brands listed below under the following part numbers:

      • Grainger: 6JY20
      • Lyn-tron: SS7431-00
      • McMaster-Carr: 94035A208
      • MSC Industrial: 67313726
      • Pic Design: 4423
      • RAF: 6931-SS
      • WM Berg: PZ-14-3

      You can also locate precision shoulder screws by Mil-Spec numbers, which include MS51575 and MS51576; all of which are DFARS compliant with full paperwork/documentation. The above mentioned shoulder screw or part, for instance, is equivalent to a Mil-Spec MS51576-14.

      At MF Supply, we offer an extensive cross-reference guide to help you discover the ideal alternative for your requirements. Explore our most popular precision shoulder screws cross reference charts below to find functional equivalents to your OEM-branded products!

      Precision Shoulder Screws Cross-Reference Charts: Find OEM Brands and Functional Equivalents

      Precision Inch Shoulder Screws with Hex & Slotted Drives in 416 Series Stainless Steel – Cross Reference Charts

      Precision inch hex socket shoulder screws and precision inch slotted shoulder screws are available in 416 Series Stainless Steel. Stock sizes include 1/8 through 1/2 diameters.

      Precision Inch Shoulder Screws with Hex & Slotted Drives in 300 Series Stainless Steel – Cross Reference Charts

      Precision inch hex socket shoulder screws and precision inch slotted shoulder screws are also available in 300 Series Stainless Steel. Stock sizes include 1/8 through 1/2 diameters.

      Precision Metric Shoulder Screws with Hex Drive in 18-8, 300 & 416 Series Stainless Steel – Cross Reference Charts

      Precision metric hex socket shoulder screws are available in 18-8, 300 & 416 Series Stainless Steel. Stock sizes include M4 through M12 diameters.

      Precision Metric Shoulder Screws with Slotted Drive in 18-8, 300 & 416 Series Stainless Steel – Cross Reference Charts

      Precision metric slotted socket shoulder screws are available in 18-8, 300 & 416 Series Stainless Steel. Stock sizes include M4 through M12 diameters.

      Precision Mil Spec Shoulder Screws with Hex Drive in 300 Series Stainless Steel – MS51576 – Cross Reference Charts

      Precision Mil-Spec hex socket shoulder screws, MS51576, are available in 300 Series Stainless Steel. Stock sizes include 4-40 through 3/8-16 diameters.

      Precision Mil Spec Shoulder Screws with Slotted Drive in 300 Series Stainless Steel – MS51575 – Cross Reference Charts

      Precision Mil-Spec slotted socket shoulder screws, MS51575, are available in 300 Series Stainless Steel. Stock sizes include 1/8 through 1/2 diameters.

      Using functional equivalents, including generics and other OEM brands’ versions of precision shoulder screws, is a practice smart manufacturer’s often use to save money and shorten lead times!

      Precision Shoulder Screws at MF Supply

      MF Supply is a leading supplier of precision shoulder screws including major brands and equivalents. We stock a huge inventory including parts that are commercial and mil-spec. Our Mil-Spec products are DFAR compliant with COC and full certifications available upon request.

      Precision shoulder screws are available in imperial, mil-spec, and metric sizes, and in type 18-8/303, 300 Stainless Steel and in 416 Stainless Steel – 316 Stainless Steel, Alloy and other exotic materials are also available for special order.

      Product Lines Include:

      Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Manufacturers eager to explore our product catalog, including our recently expanded product categories, are encouraged to visit our website at www.mfsupply.com, reach out to us at sales@mfsupply.com or request a quote. Our MF Supply team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!


      Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


      MF Supply Work With Us

      Your Purchasing Department’s Secret Weapon!
      Here are 5 reasons to buy from MF Supply

      • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
      • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
      • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
      • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
      • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

      MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.  


      Ultimate Guide: Helical Inserts, aka HELICOIL, Cross Reference Guide!

      If you’ve done your homework, you probably already know that the industrial marketplace is home to a myriad of trademarked – OEM branded expensive fasteners and components. Many branded parts have generic alternatives. Similar to how brand-name products like Kleenex® can be found generically as facial tissues, many brand-name fasteners are also available as “generics,” “crosses,” “alternatives,” or “functional equivalents.”

      In the fastener industry, a functional equivalent fastener is a part that replicates the brand-name product in form, fit, and function, including material and plating specifications, but is produced by a different manufacturer. This allows you to get the same performance and quality, often at a lower cost and with shorter lead times.

      A significant number of OEM brands out there have generic functional equivalents. Here is a shortlist of brands that have generic alternatives:

      3 Star Rivets USA, ABBATRON®, ALCOA, AMATOM®, APEX®, ARCONIC®, ATLAS®, AVDEL®, AVK®, B. F. GOODRICH, BOLLHOFF, BUCKEYE, CAPTIVE, CELUS®, CHERRY®, CONCORD, FASTENAL, GESIPA®, GLOBE ELECTRONICS, GRIPCO®, H. H. SMITH, HELICOIL®, HOWMET, HUCK, INDUX, INTERFAST, KATO®, KEENSERT®, KEYSTONE, LOCTITE®, LYN-TRON, MACLEAN­ ESNA®, MARSON®, MCMASTER-CARR, MISUMI, MSC INDUSTRIAL, PEM®, PIC DESIGN®, POP®, POWERS®, QUICKSCREWS, RAF, RECOIL®, RED HEAD®, ROTOR CLIP®, SHEREX, SIMPSON, SOUTHCO®, SPS TECHNOLOGIES, TINNERMAN®, U. S. ANCHOR, UNICORP, VIP, W. M. BERG, W. W. GRAINGER, WALDES TRUARC®.

      One example of an OEM hardware brand is the trademarked name Helicoil®. Although the name Helicoil® is often used to refer to helical inserts (also known as helical wire, wire inserts or wire threaded inserts)—similar to how Band-Aid® is used to describe adhesive bandages, Helicoil® is the registered trademark of Stanley Engineered Fastening (recently acquired by Bollhoff).

      The same helical inserts manufactured under the Helicoil® brand name are also available from alternative manufacturers under brand names such as CHRISLYNN, Recoil®, and KATO®, E-Z Lok and Powercoil. These inserts can also be identified by their Mil-Spec numbers, which include: MS122076 through MS122275, NAS1130, MS124651 through MS124850, MS21208, MS21209, MS122076, MS33537, MA3279, MA3329, and NA0276 series. Note: All of these offerings are the tanged version of helical inserts.

      Here at MF Supply, we provide a comprehensive cross-reference guide to help you find the perfect alternative to meet your needs. Check out our most popular helical inserts cross-reference charts below to see if there is a functional equivalent to your OEM branded product! They come in imperial, mil-spec and metric sizes and materials.

      Helical Inserts Equivalents Cross-Reference Charts: Find OEM Brands and Functional Equivalents

      Helical Insert Inch & Mil-Spec Cross Reference Charts

      Helical inserts, in imperial/inch & mil-spec sizes, are available as free running coarse thread (UNC), self-locking coarse thread (UNC), free running fine thread (UNF), and self-locking fine thread (UNF) in stainless steel material with Tang.

      Mil-Spec series include: MS122076 through MS122275, NAS1130, MS124651 through MS124850, MS21208, MS21209, MS122076, MS33537, and NA0276 series.

      Helical Insert Metric Cross Reference Charts

      Helical inserts, in metric sizes, are available as free running coarse thread, self-locking coarse thread, free running fine thread, and self-locking fine thread in stainless steel material with Tang.

      series include: MA3279, and MA3329.

      Using functional equivalents, including Mil-Spec, generics and other OEM brands’ versions of helical inserts, is a smart practice that manufacturers’ often use to save money and shorten lead times!

      MF Supply is a leading supplier of Helical Inserts including major brands and equivalents. We stock a huge inventory including free running coarse thread (UNC), self-locking coarse thread (UNC), free running fine thread (UNF), and self-locking fine thread (UNF) helicoil inserts in imperial/inch, mil-spec and metric sizes, and in stainless steel with tang. Our Mil-Spec products are DFAR compliant with COC and full certifications available upon request.

      Product Lines Include:

      1. Inch/Imperial & Mil-Spec Helical Inserts
      2. Metric Helical Inserts

      Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Explore our product catalog by visiting our website at www.mfsupply.com, reaching out to us at sales@mfsupply.com, or requesting a quote.. Our MF Supply team of sourcing experts is here to help find what you need. “Finding the right screw for you” is our tag line after all!


      Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


      MF Supply Work With Us

      Your Purchasing Department’s Secret Weapon!
      Here are 5 reasons to buy from MF Supply

      • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
      • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
      • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
      • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
      • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

      MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply. 


      Ultimate Guide: Standoff and Spacers Cross Reference Charts and Guide!

      At MF Supply, we specialize in sourcing hard-to-find, back-ordered, or out-of-stock OEM hardware brands in order to save you money and reduce lead times, without sacrificing quality. You might be surprised to learn that the industrial marketplace is filled with hundreds of registered trademark-branded expensive fasteners and components that have generic alternatives. Just as brand-name pharmaceuticals like Tylenol and Advil are available generically as acetaminophen and ibuprofen, certain brand-name fasteners can also be found as “generics,” “cross-references,” “alternatives,” or “functional equivalents.”

      In the world of fasteners, a functional equivalent fastener is a part that matches the brand-name product in form, fit, and function, including material and plating specifications, but is manufactured by an alternative company. Hence, the industrial marketplace is home to hundreds of fasteners and components that are registered under various trademark brands, but that offer the same function. This ensures you receive the same product performance and quality at a potentially lower cost and with shorter lead times.

      Many OEM brands have generic functional equivalents. Below is a comprehensive list of brands that have generic alternatives:

      3 STAR RIVETS USA, ABBATRON®, ALCOA, AMATOM®, APEX®, ARCONIC®, ATLAS®, AVDEL®, AVK®, B. F. GOODRICH, BOLLHOFF, BUCKEYE, CAPTIVE, CELUS®, CHERRY®, CONCORD, FASTENAL, GESIPA®, GRIPCO®, GLOBE ELECTRONICS, H. H. SMITH, HUCK, INDUX, INTERFAST, KEENSERT®, KEYSTONE, LOCTITE®, LYN-TRON, MACLEAN­ESNA®, MARSON®, MCMASTER-CARR, MISUMI, MSC INDUSTRIAL, PEM®, PIC DESIGN®, POP®, POWERS®, QUICKSCREWS, RAF, RED HEAD®, ROTOR CLIP®, SHEREX, SIMPSON, SOUTHCO®, SPS TECHNOLOGIES, TINNERMAN®, U. S. ANCHOR. VIP, W. M. BERG, W. W. GRAINGER, WALDES TRUARC®, UNICORP.

      Yes! Standoffs and spacers from various OEM brands often have functional equivalents. In fact, standoffs and spacers are sometimes referred to by their brand names, which can often be substituted by generic equivalents. Popular brands include: Amatom®, Concord, Globe, H.H. Smith, Lyn-tron, Microplastics, Keystone, Pem®, RAF, Unicorp. Their equivalents are available in a range of types, materials, sizes, and specifications.

      Here at MF Supply, we provide a comprehensive cross reference guide to help you find the perfect alternative to meet your needs. Check out our most popular standoffs and spacers cross reference charts below to see if there is a functional equivalent to your OEM branded product!

      Standoffs and Spacers Equivalent Cross Reference Charts: Find OEM Brands & Functional Equivalents

      Hex Standoffs Cross Reference Charts

      Hex Female and Hex Male-Female Standoffs in imperial/inch sizes are available in Aluminum, Brass Nickel, Nylon, 303 Stainless Steel, and Steel Zinc materials.

      Hex Male-Female Standoffs in metric sizes are available in Aluminum and 303 Stainless Steel materials.

      Round Standoffs Cross Reference Charts

      Round Female and Round Male-Female Standoffs in imperial/inch sizes are available in Aluminum, Brass Nickel, Nylon, and Stainless Steel materials.

      Hex Spacers Cross Reference Charts

      Hex Spacers in imperial/inch sizes are available in Aluminum, Brass Nickel, Nylon, and 303 Stainless Steel materials.

      Round Spacers Cross Reference Charts

      Round Spacers in imperial/inch sizes are available in Aluminum, Brass Nickel, Nylon, and 303 Stainless Steel materials.

      Standoffs and Spacers sometimes also show up under their Mil-spec numbers, which can be crossed to commercial equivalents. Some common Mil-spec series include NAS42, NAS43, NAS61, NAS1056, NAS1057, NAS1829, NAS1830, NAS1831. 

      Using functional equivalents, including Mil-Spec, generics and other OEM brands’ versions of electronic hardware like standoffs and spacers, is a practice smart manufacturer’s use to save money and shorten lead times.

      MF Supply is a leading supplier of Standoffs and Spacers including major brands and equivalents. We stock a huge inventory including imperial/inch and metric hex male-female standoffs, hex threaded female standoffs, round male-female standoffs, round threaded female standoffs, hex spacers, and round spacers. They are available off-the shelf in aluminum alloy, brass nickel, nylon, 303 stainless steel, carbon steel zinc, and steel zinc materials. Standard stock sizes run from 3/16″ to 1/2″ in body diameter and 1/4″ to 2″ in length, with threads starting from 2-56 and going up to 1/4-20; and clearance holes ranging from #2 to 1/4″. Metric stock sizes run from M3.5 to M6 in body diameter, with threads available in M2.5, M3, and M4. Most of our products are DFAR compliant with COC and full certifications available upon request.

      Imperial/Inch Product Lines Include:

      1. Hex Female Standoffs
      2. Hex Male-Female Standoffs
      3. Round Female Standoffs
      4. Round Male-Female Standoffs
      5. Hex Spacers
      6. Round Spacers

      Metric Product Lines Include:

      1. Metric Hex Male-Female Standoffs

      Manufacturers working with us can expect timely deliveries, competitive pricing, and access to expert guidance to help optimize their fastener choices. Explore our product catalog by visiting our website at www.mfsupply.com, reaching out to us at sales@mfsupply.com, or requesting a quote.. Our MF Supply team of sourcing experts is here to help find what you need. “Finding the right screw for you” is our tag line after all!


      Book a one-on-one consultation with our President, Robin, to discuss how MF Supply can help you solve your Industrial Sourcing, Fastener, and Safety concerns.


      MF Supply Work With Us

      Your Purchasing Department’s Secret Weapon!
      Here are 5 reasons to buy from MF Supply

      • We Source and Deliver What Others Can’t, Faster Than You Imagined – With speedy solutions for elusive parts and lengthy delivery times – We’ve got you covered with both custom-made specials (send us your prints!) and hard-to-source options, quickly and at a fair price.
      • Cost-Effective Functional Equivalents to OEM Brand Fasteners-Why Pay More? – Reduce lead times and costs with the same quality and same performance.  Try us for alternatives to brands like McMaster-Carr, MSC, Misumi, PEM, and RAF and experience unmatched savings! Same form, fit and function for less.  
      • Huge Selection of Certified and Commercial Hardware with Same-day Shipping Available for Countless Items – We source and stock standards, specials, commercial, Mil-Spec & OEM brands in inch and metric sizes. Standards include AN, NAS, MS, IFI, ASTM, ASME, DIN, ISO, JIS. We are sourcing experts for inserts, certified Mil-Spec parts and anything in stainless steel. Many parts are available with manufacturers’ certifications, including DFAR, ROHS and CoC. Trust us to ship on-time from our national distribution centers. 
      • A User-Friendly, 24/7 Online Shopping Experience – Enjoy a 24/7 online shopping experience with easy-to-use filters, detailed product information, and a constantly updated technical directory. Sign up now for a seamless experience! 
      • WBE/WOSB Certified Woman-Owned Small Business – As a certified Woman-Owned Small Business, we support your diversity goals. Trust us to meet your fastener and sourcing needs with expertise and efficiency [Cage Code 58QG4].  

      MF Supply is a WBE/WOSB certified supply chain partner to business, industry and government.  We are sourcing experts and stocking distributors of Hardware, Precision & Mil-Spec Fasteners and Safety supplies.  For more than 50 years, we have been supplying manufacturers in the electronics, industrial, commercial, aerospace and military markets with the full range of fastener products and services.  Our Cage Code is 58QG4 and our registered name is RL Supply Inc dba MF Supply.