The Colt LE6943CK Monolithic Upper Assembly feature's Colt's new monolithic upper receiver. In addition to an uninterrupted full-length front rail, this upper receiver allows for a free-floated barrel. This LE6943CK Monolithic Upper Assembly also features a gas-block mounted front flip-up sight with bayonet lug and a flip-up rear sight. The barrel is Colt's standard 11.5" chrome lined M4 barrel with an A2 flash hider up front.