Clevis pins are used in the automotive and aircraft industry as well as sailboat riggings. They are typically made of stainless steel and come in many sizes; unit of measure can be metric or inches. The U-shaped fastener has holes at one end of the prongs, in which the stainless steel clevis pin is inserted. Once inserted a split pin securely holds the clevis fastener in place. There are other kinds of pins that do similar jobs like cotter pins and hitch pins; choose the one that best fits your needs.