Size: .154 diameter. These are the Generation 2 Mod 3 pin sets for the POF GENERATION 3 & 4 RECEIVERS and MAY fit other receivers with ambidextrous bolt releases. They are the strongest pins that can be produced and were designed to withstand the high impact of full and semi-automatic 9mm and supressed .223/5.56 weapons. Stainless steel trigger & hammer pins are black nitrided. End retainers are black nitrided. Special anti-creep retainers prevent wear on your AR-15 receiver. Pin installation tool & 2 Torx wrenches included. No modification to gun required.