The Geissele Premium Mil-Spec Buffer Tube is machined from 7075-T6 aluminum, finished in Type 3 Hardcoat Anodize, and built to mil-spec standards. The carbine-length tube features 6 stock positions, weighs 3.7 oz, is made in the USA, and is compatible with most mil-spec-diameter AR-15 stocks. It includes a mil-spec castle nut and end plate. The Geissele Super 42 Spring improves AR-15 reliability with its unique three-strand wire design, which acts as a harmonic damper and energy absorber to reduce spring fatigue and failure. It also eliminates the common spring ,twang, and provides 15% more average return force than a standard buffer spring, helping maintain reliable function under demanding conditions.