HILLMAN 5/16 in. Zinc-Plated Steel USS Whiz Lock Nut 1 Pk

Whiz-Lock free spinning nuts have been proven to overcome vibration and a variety of other forces. The underside, or bearing surface of the fastener, has a series of spiraling serrations, or teeth, to provide a locking, reliable hold. The application of this nut is as easy as spinning it on. They simply spin on to mating thread and lock when seated per medium of toothed flange.