Belleville Spring Lock Washer Zinc-Plated Steel for Number 10 and M5 Screw Size, 100PK

These washers have smaller outside diameters than standard spring lock washers to fit neatly under socket head cap screws. Also known as conical washers these have a slightly cupped shape that gives them spring-like flexibility to grip tighter than split and tooth lock washers. They minimize loosening from wear temperature changes and vibration. Serrations on the top and bottom provide extra gripping power. Load-rated Belleville disc springs are also available.