Operation
The jaws are set to a size slightly smaller than what is to be gripped by turning the bolt in one handle with the jaws closed. Some new versions have slots in the handle bolt which can be further tightened with a hex key or screw driver. When the jaws are opened and the handles squeezed together, they move a lever over its center point and lock the jaw of the pliers onto the gripped object. A typical usage would be to hold metal parts in place for welding. They are also invaluable for holding a nut or bolt that has been 'rounded' or as temporary levers/knobs on equipment and machinery.