Aero Precision M5E1 (.308) Enhanced Upper ReceiverThe 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.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 of Aero Precision M5E1 (.308) Enhanced Upper Receiver: M4 Feedramps .2795 takedown pin holes Laser engraved T-marks Comes assembled, with dust cover and forward assist installedM5E1 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(R) Armorer's Wrench)Includes: M5E1 Upper Receiver in Anodized Black Port Door and Forward Assist installed Barrel 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.