5/8"-11 18-8 Stainless Steel Coarse Thread Lock Nuts (4 pcs.)

Diameter: 5/8"
Diameter 2: 1-3/32"
Thickness: 25/32
Material: Stainless Steel
Driver Type: 15/16" Wrench
Thread Size: 11 (Coarse)
Hardness: 18-8
Style: Waxed Nylon Insert
Type: Lock Nut

Box of 4.

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