The spring-loaded piston is compressed under the workpiece. After the workpiece is clamped, air is applied to lock into position. Release the air to unlock the piston. The piston is tapped to accommodate a work support tip. Body made from anodized 5052A aluminum. Piston made from SK95 steel, quenched and tempered, with a black oxide finish. Locking shaft made from 1045 steel with an electroless nickel plated finish.