This AR-STONER upper features a 7.62x39 (0.308")barrels and enhanced firing pin for increased reliability for steel cased ammo and upgraded bolt. The A3 upper will attach to virtually any standard AR-15 lower receiver and comes complete with charging handle, forward assist, ejection port cover, A2 flash hider, bolt and bolt carrier assembly. Supplied without a rear sight, this upper is a great platform for a red dot sight or iron sights (both sold separately). Features:Parkerized 4150 Chrome Moly Vanadium BarrelBillet receiver15" MLOK RailRear Charging