OEM for Colt AR-15 Lower Parts Kit Includes everything that goes inside your stripped lower receiver. Includes fire control group, the pins and springs for the fire control group, bolt catch assy., mag catch assy., front pivot pin, rear takedown pin, 2 takedown pin springs, 2 takedown pin detents,  A-2 pistol grip, pistol grip screw, pistol grip screw washer, buffer detent, and buffer detent spring.