Our state of the art M5E1 platform starts here, with the M5E1 Upper Receiver. The M5E1 upper receiver is a one-piece design combining the handguard mounting platform with the upper itself. Through superior engineering, we 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 we are able to make additional lightening cuts to save weight and allow for more efficient cooling. Ease of installation - Simply insert your barrel assembly into the M5E1 upper, tighten it using the included barrel nut and slide your rail on and tighten the rail screws. Within minutes you have a modular, free-floated rail. Features: M4 Feedramps .2795 takedown pin holes Laser engraved T-marks Comes assembled, with dust cover and forward assist installed M5E1 Specific Details: Handguard mounting platform is forged into the receiver Works with Aero Precision M5 Enhanced Handguards Barrel nut included Torque to 65 ft. lbs. with an armorer's wrench (we recommend a TAPCO