Atlas BT65 Bipod BTC-Pro Dual Arca and Picatinny Mount 4.75-9 Inches Black. The BT65-NC model Atlas Bipod is part of their CAL Series. The NC stands for No Clamp, meaning it requires any 17S size mount to attach to a firearm. The interface to install a clamp has a two hole pattern of 1.100 inches with 10-32 threads. It will also mount directly to BT19 AI Spigot or BT70 M-LOK Adapter. The BT65-NC is comprised of 6061-T6 aluminum that is Mil-Spec Type III hard coat anodized with treated stainless steel components. Includes two 10-32 x 3/8 inch flathead socket screws.