They are used as a locking device to hold pins or castle nuts in place. Cotter pins are wire formed pins with two prongs that separate during installation.1/16" x 1" Cotter Pin Clip, 150PK These low-cost and highly versatile fasteners are used virtually everywhere..
R-160 Square O-Ring (ID: 5 1/4", CS 3/32", OD 5 7/16"), 6PK The o ring is placed into a groove to secure them in place, and then compressed between two surfaces.