Yankee Hill Trigger Hammer Pin Kit is a Anti-Rotation Hammer and Trigger Pin Kit. These pins are the strongest that are produced and are designed to withstand the high impact of full and semi-automatic 9mm and .223 suppressed weapons. An absolute must-have for all M-16 owners. Special anti-creep retainers prevent wear on your irreplaceable M-16 receiver. They will also protect your AR-15 from wear. Pin installation tool and 2 Allen wrenches are included. No modification to gun is required. The pins are made from stainless steel and the end retainers are black oxide steel.