9/16"-18 Zinc Plated Grade 2 Steel Fine Thread Nylon Insert Lock Nuts (8 pcs.)

Diameter: 9/16"
Diameter 2: 1"
Thickness: 21/32"
Material: Steel
Finish: Zinc
Driver Type: 7/8" Wrench
Thread Size: 18 (Fine)
Hardness: Grade 2
Style: Nylon Insert
Type: Lock Nut

Box of 8.

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