The Aero Precision EPC-9 Complete Lower Receiver is the perfect base for your custom AR9 build. This lower receiver comes without a stock/brace giving the builder flexibility to choose exactly what configuration they want the first time. Includes: EPC-9 Lower Receiver A2 Grip Lower Parts Kit Enhanced Buffer Tube EPC 7.7oz Buffer M5 Carbine Buffer Spring Castle nut/end plate These parts are installed EPC-9 Lower Receiver Features: Threaded bolt catch pin for easy installation