The BT65-NC CAL Atlas Bipod “No Clamp” model requires any 17S size lever style mount to include the ADM- 170-S, ARMS 17S , TRAMP from Badger Ordnance or LT271. The BT65-NC will also mount directly to the BT19 and BT21. The BT65-NC has larger Inner legs, patented 5 leg positions that do not rotate found on the Atlas PSR series. B& T Industries Atlas CAL Bipod No Clamp for BT19, ADM-170-S, ARMS 17S, TRAMP, LT171 BT65-NC