the SHAPE Super mafer clamp is made of sturdy aluminum to offer maximum clamping pressure. The protective pads in the jaws offer very strong gripping action. To close the jaws, the SHAPE super mafer clamp has a ratchet knob for additional flexibility. It also has a 5/8” (16mm) female receptor which accepts accessories with matching studs, spigots or snap-in pins. Our mafer clamp also includes a removable impact wedge insert, used for flatter surfaces. Three ¼-20 threaded holes are also included to attach additional accessories.