Rock River Arms RRAGE 3G, Complete Upper Receiver, 223 Remington/556NATO, 16 Barrel, A2 Flash Hider, RRA 15 Free Float M-LOK Handdguard, Anodized Finish, Black, Fits AR-15, Includes Bolt Carrier Group and Charging Handle Assembly BB0470 Rock River Arms RRAGE 3G A4 carbine upper comes chambered in 5.56mm NATO. This extruded aluminum upper receiver comes with a port door and no forward assist. Additionally" this upper is equipped with a RRA 15" RRAGE 3G M-Lok compatible handguard" a 16" chrome moly barrel" A2 flash hider" bolt carrier group and charging handle assembly.