Includes everything that goes inside your stripped lower receiver. Includes M-16 fire control group, M-16 Sear, the pins and springs for the fire control group, bolt catch assy., mag catch assy., front pivot pin, rear take down pin, 2 take down pin springs, 2 take down pin detents, A-2 pistol grip, pistol grip screw, pistol grip screw washer, buffer detent, and buffer detent spring.