Hex Socket Swivel Screw Clamp With Large Pad – 1/4-20 Thread X 23/32. Use When Space Is Limited And Greater Clamping Pressures Are Needed. Pad Can Be Detached From Body Via A Left Hand Thread. When Using, Thread Body Through Hole, Then Screw Pad Onto Body On Other Side Of Hole. When Pad Comes Into Contact With Part Or Workpiece, It Stops Rotating And Thus Prevents Marring. Black Oxide Finish.