Steel cotter pin fastens material together, similar to a staple or rivet, by locking clevis pins, slotted nuts, and other fasteners. Pin has two easy-to-open prongs, with one longer than the other. The general-purpose steel offers strength in a range of applications. It has a plain finish and should be used where corrosion is not a concern. A cotter pin is a metal fastener with two prongs that are bent during installation. Typically made of wire with a half-circular cross section, cotter pins may be used in some applications as low-tech shear pins.