5/8"-11 Black Phosphate Grade 2 Lock Nuts LNS-419 (74 pcs.)

Diameter: 5/8"
Diameter 2: 1-7/32"
Thickness: 35/64"
Material: Steel
Finish: Black Phosphate
Driver Type: 15/16" Wrench
Thread Size: 11 (Coarse)
Hardness: Grade 2
Style: Top Lock|Type C
Type: Lock Nut

Box of 74.

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