SilencerCo SU4766: The SilencerCo AR-15 Lower Receiver is made from billet 7075-T6 aluminum. It is precision machined for compatibility with all of your preferred parts. The lower receiver is finished in a type III hard-coat anodized for added durability and corrosion resistance. The new design includes a proprietary ambidextrous bolt catch, integrated enlarged trigger guard, and ambidextrous multi-position sling swivels, as well as various other features. With the SilencerCo Billet AR-15 receiver, you get the materials, finish, and features you want and need to complete your dream AR-15 build.