The Geissele Automatics premium grade MIL-SPEC AR-15 buffer tube, built from the ground up to meet or exceed military specifications. Precision machined from quality 7075-T6 aluminum, this heavy duty 6-position receiver extension is fully compatible with your favorite MIL-SPEC-diameter carbine stocks. Topped off with a tough black Type III hardcoat anodized finish, the Premium MIL-SPEC buffer tube is a great option for your next build. It even includes a castle nut and end plate!