LBE Unlimited is a quality manufacturer of AR-15 parts and accessories. This particular item is an AR-15 pistol buffer tube/receiver extension. This buffer tube can be used as a replacement unit or as a spare for a new build. This unit is pre-threaded and will install easily to any standard pattern AR-15 lower receiver. Features: Black finish AR-15 pistol buffer tube Pre-threaded Compatible with Mil-Spec AR-15 lower receivers and similar pattern units