The Aero Precision EPC-9 Enhanced Upper Receiver is the perfect addition to any AR9 build. Including a last round bolt hold open mechanism and compatible with Aero Precision's robust lineup of Enhanced and Quantum handguards, the EPC-9 Enhanced Upper Receiver provides an extremely rugged handguard mounting solution.The EPC Enhanced Upper Receiver utilizes a one-piece design combining the handguard mounting platform with the upper receiver itself. Through superior engineering, Aero Precision has 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 Aero Precision is 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 EPC Enhanced upper, tighten it to spec using the provided barrel nut and wrench, slide your rail on and tighten the rail screws. ...