5/16" x 1/2" Zinc Plated Steel Wavy Washers

Nominal Size: 5/16"
Inside Diameter: 5/16"
Outside Diameter: 1/2"
Thickness: 1/16"
Material: Steel
Finish: Zinc
Style: Wavy
Type: Lock Washer

Box of 20.

The purpose for a lock washer is to prevent threaded fasteners from loosening by creating friction between the fastener and the mounting surface.