Swordfish 30330 - 210pcs Nylon Insert Lock Nut Assortment - #4-40 to 5/8"-11 - Zinc Plated Steel
 
Hex Nut with a nylon-filled collar at its back end. When a screw reaches the collar, the threads and nylon form a tight, frictional fit, restricting movement of the screw when it is subjected to vibration.
Designed to be used with like-material machine screws and bolts. It is able to be reused more times than a two-way reversible nut
Steel nylon insert stop nuts are less expensive than grade C automation lock nuts.
AISI 1008-1010 or equivalent steel material used.
Hardness: Rockwell C28 maximum and Proof Load: 90,000 PSI minimum