Stag Arms Cal.223 Stripped Lower Receiver. All Stag Arms receivers are military spec. and made of forged 7075 T6 Aircraft quality aluminum. They are bead blasted and coated with TYPE III CLASS 2 HARD COAT to insure strength, and durability. Lower uses standard military spec. take-down and fire control pins. Lower is compatible with all military spec. uppers: Bushmaster, DPMS, Armalite etc. Receivers are RDIAS/RLL compatible for your NFA registered drop in auto sear or registered lighting link.Additional photos on request.