Strong yet light weight these handy little clamps with die-cast zinc sliding jaws can easily create 330 pounds of clamping force. The U-shaped bar helps to clamp over small obstruction so you can get to those hard -to-reach places. The LM series clamps may be small in stature, but big on full sized features such as an ACME threaded screw for quick smooth operation. Serrated rail for slip resistance and non-marring soft pressure pads on the jaws. BESSEY. Simply better.