3/8"-24 Zinc Plated Grade 2 Steel Fine Thread Kep Lock Nuts (10 pcs.)

Diameter: 3/8"
Diameter 2: 21/32"
Thickness: 3/8"
Material: Steel
Finish: Zinc
Driver Type: 9/16" Wrench
Thread Size: 24 (Fine)
Hardness: Grade 2
Style: Kep
Type: Lock Nut
Washer Diameter: 21/32"

Box of 10.

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