The Really Right Stuff SOAR BTC-Pro system is based on both the NATO Picatinny Standard and their RRS 1.5"" Dovetail Standard. A screw knob style clamp designed to directly thread onto A.R.M.S. 17S compatible Thunderbeast, B&T Atlas and Magpul bipods. You will now be able to mount anywhere along your rifles standard picatinny rail, RRS SOAR custom chassis mount, multi-purpose rail, or full length chassis RRS/Arca rail. Clamp jaws open and close by twisting the knurled knob on our tried and true screw-knob clamps. Mfg: Really Right Stuff