NC Star Buffer Tube and Castle Nut Features The NcSTAR Buffer Tube and Castle Nut is built to the mil-spec 6 position standard meaning it is sized to accept the wide range of mil-spec collapsible buttstocks already on the market. Precision machined from aircraft grade aluminum the tube holds its dimensional tolerances under the repeated stress of extending and collapsing a stock in the field. This level of material quality supports long term durability even under hard frequent use. The included castle nut secures the tube to the receiver extension threads completing the mounting hardware needed for a proper buttstock installation. A hard anodized black finish coats the tube adding a layer of wear and corrosion resistance beyond what a bare aluminum surface would offer. This finish also gives the tube a clean uniform look that matches most black AR-15 builds. Because it follows mil-spec dimensions rather than a commercial spec the tube offers broader stock compatibility for builders mixing components from different manufacturers. Anyone building repairing or upgrading an AR-15 stock system will find this buffer tube a reliable mil-spec correct foundation. NC Star Buffer Tube and Castle Nut Specifications Manufacturer: NC Star Model: Buffer Tube and Castle Nut Type: Buffer Tube Color: Black Compatible Hosts: AR Rifles Size: Mil Spec Finish: Matte Anodized Available At: GrabAGun