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304 Stainless Steel Solid Brass
316 Stainless Steel Yellow Zinc Grade C
Zinc Plated Grade A Heavy Zinc Plated Grade A

Stainless Steel Lock Nuts

Nylon Insert Lock Nuts

Lock Nuts with a Nylon Insert Stopper

A nylon insert lock nut is hex shaped, internally threaded with a nylon insert. The nylon material prevents loosening from vibration and cross threads to stop the nut from backing off of the fastener. The insert deforms elastically over the threads of the screw, but threads are not cut into the nylon. The nylon insert locks the nut in two ways. First, it forces the bottom face of the screw threads against the top face of the nut threads, increasing the friction between the two. Second, the nylon applies a compressive force against the screw itself. They come in a variety of materials.

304 Stainless Steel

Also known as 18-8 Stainless steel, this is the standard grade for stainless steel fasteners. They are corrosive-resistant and durable. Stainless alloy resists oxidizing and rusting, however it can tarnish over time.

316 Stainless Steel

This grade of stainless steel is used and recommended for applications in severe, harsh or marine environments. Its corrosion resistance is greater than 18-8 stainless, which is why we recommend using 316 stainless steel fasteners for salt water application.

Grade C Yellow Zinc

Grade C is a thru-hardened medium carbon steel. No head markings (manufacturers mark may also be included). Finish is equivalent in strength to Grade 8. Zinc adds a further layer of corrosion resistance to the Grade C fastener.

Zinc Plated Grade A Steel

Nylon insert lock nuts in this selection are case-hardened (CR+3) Zinc Plated Grade A Steel. This adds a layer of protection to the fastener, as well as hardening the steel.

Heavy Nylon Lock Nuts

Heavy nylon insert lock nuts are thicker than standard nylon lock nuts, making them more suited for heavy-duty applications.


For more information on fastener types, grades, and materials, please visit our Fasteners 101 page here

To prevent or stop galling (also known as seizing or locking-up) on stainless steel fasteners, we recommend using an anti-seize thread lubricant from our line of MRO Solutions