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 holesLazer engraved T-marksComes assembled, with dust cover and forward assist installedM5E1 Specific Details:Handguard mounting platform is forged into the receiverWorks with Aero Precision M5 Enhanced HandguardsBarrel nut includedTorque to 65 ft. lbs. with a standard AR15 Armorer’s WrenchIncludes:M5E1 Upper Receiver in FDE CerakotePort Door and Forward Assist installedBarrel NutPlease Note – – The M5E1 Upper Receiver is specifically designed to be used with our M5 Enhanced Handguards. It will not work with other AR10/308 handguards.