This listing is for a variety of AR-15 lower receiver parts. Included in this bundle is a standard M4 stock, old school style CAR 15 stock, A2 style hand grip, A1 style handgrip, four position buffer tube, buffer spring and buffer, slim CAR handgrips, SPR Sierra Precision grip, Colt trigger and hammer with pins, KAC rail covers, two buffer tube end plates, castle nut, and P&S vertical grip.