Machined aluminum receiver extension tubes accept an M4-style adjustable carbine buttstock. Six precision-machined notches on the underside provide plenty of options for setting length-of-pull. Perfect for a custom build, installing a mil-spec or commercial stock on a civilian carbine, or updating a fixed-stock rifle with an adjustable M4 stock. Machined from a lightweight aluminum extrusion then hardcoat anodized, and dry film lube-coated inside for smooth movement of the buffer and buffer spring. Requires carbine recoil spring and buffer, lock ring, and receiver plate, all available separately.

SPECS: Aluminum, hardcoat anodized, matte black. 7-7?8" (20cm) long. Mil-spec – 7-3/16” (18.25cm) long, 1.145" O.D. Commercial – 7-7?8" (20cm) long, 1.167 O.D.