Diameter: 5/16"
Diameter 2: 9/16"
Thickness: 23/64"
Material: Steel
Finish: Black Oxide
Driver Type: 9/16" Wrench
Thread Size: 18 (Coarse)
Style: Nylon Insert
Type: Lock Nut

Box of 8.

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