The jaws move forward and downward as the ball screw is tightened. The jaws swivel 1.5 degrees from center to allow for clamping on uneven surfaces. Tightening the ball screw forces the clamp forward and downward against the work piece supports and stops. The body is made from SAE-1045 alloy steel. The arm is made from SAE-1045 alloy steel and heat treated. The replaceable jaws are serrated for positive holding and are made from M-2 high speed steel, hardened to Rc 60/62. Parts have black oxide finish.