A2 is the classic AR-15/M16 style for muzzle devices, sights, and stocks. The flash hider fits 5.56/.223 barrels with a 1/2 x 28 thread to cut muzzle flash. The front sight post works with standard AR-15 barrels and gas blocks. The fixed stock fits rifle-length buffer tubes and lower receivers. These parts give your rifle traditional military styling and solid performance.