Cotter Pins, or a split pin, is a metal fastener with two lines that are bent during installation to hold a metal rod in place. Once removed they should be replaced with a new cotter pin due to the fatigue from bending the metal during installation and removal. Common materials for these fasteners are steel, brass, bronze, aluminium, and stainless steel. Monroe Aerospace is a stocking distributor of Aerospace and Mil-Spec hardware. We have an extensive inventory of cotter pins. Every part that we sell is in Factory new (FN) condition and we provide our company’s certificate of conformance for all parts on every order. See below for our products.