Stop nuts and screws from loosening due to mild vibration. As you tighten, the uneven ends bite into the nut or screw so it won't back out. While they're not as vibration resistant as other lock washers, they are a great fit for electrical panels, light fixtures, and other light duty assemblies. Split lock washers are not reusable, and they only work with fasteners that have right-hand threads.

Zinc-Yellow-Chromate-Plated Steel—With the same corrosion resistance as zinc-plated steel, these withstand occasional exposure to moisture.