1/2"-13 Black Phosphate Grade 2 Nylon Insert Lock Nuts LNS-417 (117 pcs.)

Diameter: 1/2"
Diameter 2: 27/32"
Thickness: 39/64"
Material: Steel
Finish: Black Phosphate
Driver Type: 3/4" Wrench
Thread Size: 13 (Coarse)
Hardness: Grade 2
Style: Nylon Insert
Type: Lock Nut

Box of 117.

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