LBE Unlimited Complete Stock Kit, Fits AR-15, Contains Mil-Spec Dia Stock, Buffer Tube, Castle Nut, Lock Plate, Black MILSTKKT This LBE stock assembly kit includes a classic M4 style adjustable buttstock" six position mil-spec buffer tube" carbine length recoil spring" standard carbine recoil buffer" receiver end plate" and castle nut. LBE Unlimited is a leading producer of US Made gun parts and accessories.