1/4"-28 Zinc Plated Grade 2 Steel Fine Thread Top Lock Nuts LNS-269 (16 pcs.)

Diameter: 1/4"
Diameter 2: 1/2"
Thickness: 7/32"
Material: Steel
Finish: Zinc
Driver Type: 7/16" Wrench
Thread Size: 28 (Fine)
Hardness: Grade 2
Style: Top Lock|Type C
Type: Lock Nut

Box of 16.

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