This Bushmaster XM15 QRC (Quick Response Carbine) upper will attach to virtually any standard AR-15 lower receiver. Comes complete with charging handle, forward assist, ejection port cover, bolt and bolt carrier assembly. With a 1 in 8" twist, the 16" barrel provides outstanding accuracy that has been enjoyed by competition shooters worldwide. Pre-ban style upper includes a bayonet lug and flash hider. Supplied without a rear sight, this upper is a great base for a red dot sight or iron sights.