Rock River Arms Tactical Carbine, Complete Upper Receiver, 450 Bushmaster, 16" Barrel, Mid-Length Gas System, RRA Operator Muzzle Brake, RRA 13" Free Float M-LOK Handguard, Anodized Finish, Black, Fits AR-15, 5 Rounds, 1 Magazine, Includes Bolt Carrier Group and Charging Handle Assembly 450B0592