Ultimate Guide: Inch, Mil-Spec, and Metric Keensert® Equivalent Cross Reference Guide!
Posted: April 12, 2024 Filed under: Alloy Keenserts, Carbon Steel Keenserts, Cross Reference Charts, Inch and Mil-Spec Keensert, keensert, key-locking inserts, Metric Keensert, Stainless Steel Keenserts | Tags: Hardware, Imperial Keenserts, Keensert Cross Reference Charts, Keenserts, Keenserts Cross Reference, Key-locking Inserts Cross Reference, Keylocking Inserts Cross Reference, manufacturing, metric keenserts, mil-spec keenserts, MS51830, ms51831, MS51832, Precision Engineering, Precision Manufacturers, threaded inserts Leave a commentAt 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. In fact, you can find hundreds of registered trademark-branded fasteners and components in the industrial marketplace. Much like brand-name pharmaceuticals such as Tylenol and Advil are available generically as acetaminophen and ibuprofen, some brand name fasteners are also available as “generics,” “crosses,” “alternatives” or “functional equivalents.”
In the world of fasteners, a functional equivalent fastener is a part that is the same as the brand-name product in form, fit and function, including material and plating specifications, but is made by an alternative manufacturer.
Is There an Available Functional Equivalent to My OEM Brand?
Below, find a sample 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®.
Do Keenserts® Have Functional Equivalents?
One example of an OEM hardware brand is the trademarked names Keensert®and Keysert®. Although the name Keensert® is often used to describe a Key-locking insert — like Band-Aid® is used to describe an adhesive bandage, or like Kleenex® is used to describe facial tissues — Keensert® is the registered trademark of Huck Patents; its close cousin, the Keysert®, is a registered trademark of Alcoa Fastening Systems.
The same key-locking inserts manufactured under the Keensert® and Keysert® brand names are also available (or have been available in the past, prior to industry consolidation) from alternative manufacturers under brand names such as Acme, Camloc, Clarendon, Fairchild, Kaynar, Microdot, Rexnord and Tridair. You may also find Keenserts® under their Mil-Spec numbers, which include MS51830, MS51831, MS51832 and NA series. Keenserts® come in imperial, metric and mil-spec sizes and materials.
Below, checkout our three most popular key-locking insert cross reference charts, to see if there is a functional equivalent to the Keensert® you need.
Keensert® Equivalent Cross Reference Charts: Find OEM Brands, Mil-spec & Functional Equivalents

Miniature, Thinwall & Lightweight, Heavy Duty, Extra Heavy Duty, Key-locking Inserts in Stainless Steel, A286, 4140 Alloy. Includes MS51830, MS51831, MS51832, NAS1394, NAS1395, KN, KNC, KNH, KNHX, KNL & KNCL Series.

Metric Keensert® Cross Reference Chart – 4140 Alloy | A286
Miniature, Thinwall & Lightweight, Heavy Duty, Key-locking Inserts in A286 and 4140 Alloy. Includes NA0146, NA0147, NA0148, NA0149, NA0150, NA0151, KN, KNC, KNL & KNCL Series.

Metric Keensert® Cross Reference Chart – Stainless Steel
Miniature, Thinwall & Lightweight, Heavy Duty, Keylocking Inserts in Stainless Steel, KN, KNC, KNL & KNCL Series.
Keensert® Style Key-Locking Inserts at MF Supply
MF Supply is a leading supplier of Keensert® style key-locking inserts including major brands and equivalents. We stock a huge inventory including Miniature, Thinwall, Lightweight, Heavy Duty, Extra Heavy Duty, Locking, Non-Locking, Solid and Floating style Keenserts®. Our Mil-Spec products are DFAR compliant with COC and full certifications available upon request.
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.
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.
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Carbon Steel Key-Locking Inserts (AKA Keenserts®) at www.mfsupply.com
Posted: January 26, 2024 Filed under: Brand equivalents, Carbon Steel Keenserts, Fasteners, Inch and Mil-Spec Keensert, keensert, key-locking inserts, Metric Keensert, Threaded Bushing, Threaded Fasteners | Tags: Carbon Steel, Carbon Steel Keenserts, Carbon Steel Key-Locking Insesrts, Fasteners, inch keenserts, Inserts, inserts for manufacturers, Keenserts, manufacturing, metric keenserts, mil-spec keenserts, RKK, RKK Keenserts, threaded bushing, threaded fastener Leave a commentMF Supply is an expert and industry leader when it comes to key-locking inserts, commonly known by the popular brand name Keensert®. We stock and source key-locking inserts in a wide variety of materials, platings and sizes, including Inch, Metric, Commercial and Mil-Spec options.
In today’s blog, we will showcase a comprehensive overview of Carbon Steel Key-Locking Inserts, covering their benefits, uses, styles, standards, sizes, and comparison with other key-locking inserts made from other materials — so you are all set before jumping off to procure them for your next project.
What are Carbon Steel Key-Locking Inserts?

Carbon Steel Key-Locking Inserts, often referred to in industry vernacular as Carbon Steel Keenserts®, are precision-engineered threaded inserts predominantly fabricated from high-grade carbon steel.
Featuring both internal and external threads, these inserts are adept at providing wear-resistant thread interfaces in substrates that are inherently susceptible to thread degradation or are insufficiently robust for the intended mechanical loads. The external threading of these inserts exhibits a larger diameter and pitch compared to the internal threads, ensuring a secure engagement with the parent material.
These components are specifically designed for thread reinforcement and repair applications across a broad spectrum of parent materials. Their key-locking mechanism involves the deployment of keys integrated into the insert body. Upon installation into a pre-tapped hole, these keys are driven outward into the parent material, thereby affording a secure mechanical lock that resists rotational and axial forces. Hence, this feature is pivotal in applications where vibrational loads or cyclic stresses are prevalent.
The versatility of Carbon Steel Key-Locking Inserts makes them beneficial for any sector requiring durable, reliable threaded connections, especially where materials are subject to wear, high stress, or require thread repair and reinforcement.
What Styles, Standards & Sizes Are Available?
Carbon Steel Keenserts®, or Key-Locking Inserts, have different styles in order to cater to a wide range of application requirements and material conditions. The distinct styles are designed to address specific challenges such as load capacity, space constraints, installation requirements, and the physical properties of the base material. Below is a list of all the styles available for these Key-Locking Inserts:
- Thin Wall | RKKA | KNM: These are used when minimal space is available or in applications where less material needs to be removed. They offer a good balance between strength and size. Available off the shelf in Internal Thread 10-24 through 1/2-20 and Metric M5-M12. Often referred to by their original Fairchild part numbers: RKKA
- Heavy Duty | RKK | KNHM: Designed for higher strength and durability, these are suitable for applications subject to high stress or where a stronger thread is required. Available off the shelf in Internal Thread 8-32 through 1-1/2, and Metric M4-M24. Often referred to by their original Fairchild part numbers: RKK
- Extra Heavy Duty | KNHXH: These inserts are used in extremely demanding applications where very high pull-out and torque resistance is needed. Available off the shelf in Internal Thread 6-32 through 1-12. No standard Metric option available. Often referred to by their original Fairchild part numbers: KNHXH
- Solid | KNJ: Unlike other types have both internal and external thread, solid inserts have only external thread. Once installed, they can be drilled and tapped as required. These solid inserts can be used to relocate misplaced holes, customize the internal threads, or plug existing holes. They are extremely durable but might require more installation space. Available off the shelf in External Thread 3/8-16 through 1-1/4 and Metric M8-M32. Often referred to by their original Fairchild part numbers: KNJ.
Commonly available in diameters from 6-32 through 1-1/2, Carbon Steel Key-Locking Inserts can be used in a wide range of applications from small electronics to heavy machinery. The thread pitch varies accordingly, with finer pitches for delicate applications and coarser pitches for heavy-duty applications.
Carbon Steel Key-locking inserts are generally offered as commercial parts, and don’t have a Mil-Spec equivalent. They come standard with a phosphate finish.
*Note – Carbon Steel Key-locking Inserts do not come with a Self-Locking option, which is a standard option with Stainless Steel Keenserts®.
The Carbon Steel Difference!
How do Carbon Steel Key-Locking Inserts stack up against other materials? Here’s the breakdown:
- Stainless Steel: Stainless Steel Keenserts® are known for their corrosion resistance, especially in marine and chemical environments. However, Carbon Steel Key-Locking Inserts are generally stronger and more wear-resistant, which is beneficial in applications where the primary concern is strength rather than exposure to corrosive elements.
- 4140 Alloy Steel: This is a high-carbon alloy steel that provides excellent wear resistance and strength. While 440 Alloy Steel Keenserts® offer superior hardness, Carbon Steel Key-Locking Inserts typically excel in toughness and are more ductile, making them less likely to crack under high stress.
- A286: A286 is an iron-nickel-chromium stainless steel alloy known for its high strength and corrosion resistance at elevated temperatures. Carbon Steel Key-Locking Inserts may not match the high-temperature performance but are significantly more cost-effective for applications where extreme temperatures are not a concern.
- Nitronic 60: This material provides excellent galling and wear resistance. While it is superior in environments where these factors are critical, Carbon Steel Key-Locking Inserts offer a better balance of strength and cost-efficiency for general-purpose use.
- Inconel: Known for its ability to withstand extreme temperatures and corrosion, Inconel is often used in high-temperature applications. Carbon Steel Key-Locking Inserts, on the other hand, are more widely used in applications where high temperature and corrosion are not as critical but where high strength and lower cost are important.
Hence, Carbon Steel Key-Locking Inserts offer an excellent balance of performance and value, making them a preferred choice for applications where the benefits of higher-cost, specialized materials are not required. They stand out for their strength, toughness, and cost-effectiveness, providing a reliable and affordable solution for thread reinforcement and repair.
Carbon Steel Key-Locking Inserts at MF Supply!
MF Supply is a WBE/WOSB certified business, and a leading supplier of Carbon Steel Key-locking Inserts (AKA Keenserts®) for manufacturers, government and industry. At MF Supply, we understand the dynamic needs of the industry, including the balance of price, quality, availability and certification paperwork. Ready to see how we can help you make a difference?
Visit our website or browse through the links provided below to discover the perfect Carbon Steel Key-Locking Inserts for your next project!
Inch Carbon Steel Key-locking Inserts:
- Miniature & Thin Wall Styles Series
- Heavy Duty & Thick Wall Style Series
- Extra Heavy Duty Style Series
- Solid Style Series
Metric Carbon Steel Key-locking Inserts:
Note – Installation requires a drill bit, a standard tap, an installation tool, and a hammer. Feel free to ask us about Keensert® Kits available for many Carbon Steel sizes. Kits include a minimum of 2 inserts, a drill bit, a tap and an installation tool.
Do you still have questions or would like to speak with a representative? Reach out to us, and our MF Supply team of sourcing experts will help you find what you’re looking for. “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.
Six Reasons To Buy From MF Supply
- Creatively Solve Problems – We are sourcing experts and specialize in hard to find parts. We offer custom manufacturing and reworking solutions at competitive pricing, reducing long deliveries.
- Functional Equivalents To Expensive Brand Names- We stock and source alternatives to brand name fasteners, reducing long lead times and saving you money.
- Full eCommerce Enabled Website With Technical Manual Available 24/7 – Visit our website and Create a New Account, track online orders, browse our product catalog, check technical specs, subscribe to our blog, or buy online. We are adding items and improving functionality daily!
- Same Day Shipping From The USA – Our hardware products are in stock and ship to you directly from our USA based distribution centers.
- One-Stop Shopping On Certified Hardware – We stock and source a full line of fasteners including Mil-Spec, DFARS compliant and other industrial products.
- WBE/WOSB Woman Owned Certified Small Business – To meet your diversity & set-aside needs.
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, with an expertise in inserts, military fasteners and stainless steel hardware. 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.



