Item description for 5/16"-18 Zinc Free Spinning Washer Nuts (50 pcs.)

Diameter: 5/16"
Material: Steel
Finish: Zinc
Thread Size: 18 (Coarse)
Style: Free Spinning Washer
Type: Lock Nut

Box of 50.

A lock nut is a nut that resists loosening under vibrations and torque.