Strong yet light weight these handy little clamps are made of quality durable material. with die-cast zinc sliding jaws, it can easily create 330 pounds of clamping force. 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 pad on the end of the spindle. BESSEY. Simply better.