BT10-NC-No Clamp model (No Clamp meaning it does not have the means to attach to a rail) it requires any 17S size lever style mount to include the ADM-170-S, ARMS 17S , TRAMP from Badger Ordnance and LT271 or the BT10-NC will mount directly to our BT19 (AI) and BT21 (TRG) spigots.