3/8"-24 Polished 18-8 Stainless Nylon Insert Lock Nuts (5 pcs.)

Diameter: 3/8"
Diameter 2: 5/8"
Thickness: 7/16"
Material: Stainless Steel
Finish: Polished
Driver Type: 9/16" Wrench
Thread Size: 24 (Fine)
Hardness: 18-8
Style: Nylon Insert
Type: Lock Nut

Box of 5.

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