The Hillman Group 43981 .093 X 2-1/2 Hitch Pin Clip, Stainless Steel, 12-Pack

A hitch pin clip is a fastener used to prevent a wheel or other rotating part from sliding off the axle upon which it is riding

Some types have a clip for extra security

Stainless Steel

Also known as a hairpin cotter or R-clip, this hitch pin is used to secure the ends of round shafts most commonly on tractors or heavy equipment. Insertion into a hole depends on the straight leg entering the hole and the curved leg pressing down upon outer diameter of the shaft. Compared to cotter pins, hitch pins are easier to remove and are reusable.
Brand: Hillman, Model: 43981