This upper receiver features the same tried-and-true construction and aesthetics as Aero's M4E1 Enhanced Upper Receivers, without provisions for a forward assist. The M4E1 Enhanced Upper Receiver is a one-piece design combining the handguard mounting platform with the upper receiver itself. Through superior engineering, they have condensed the parts needed to mount a free-floated handguard to a mere 8 screws. Since the handguard mounting surface and upper are of the same forging, not only is it a stronger system, but they are able to make additional lightening cuts to save weight and allow for more efficient cooling. Ease of installation - Simply insert your barrel assembly Mfg: Aero Precision