The AR-STONER 9mm Heavy Buffer is perfect for your 9mm AR-15 Carbine. A heavy buffer slows the speed of the bolt during recoil and decreases the force exerted on the bolt catch. The steel construction provides outstanding durability and a wear resistant finish. Whether you are building a new 9mm AR-15 Carbine, or upgrading a rifle; the AR-STONER 9mm Heavy Buffer is an excellent part for the price. FeaturesBlack Polyurethane BumperStainless Steel Body4" LengthOne Solid Piece