Abstract: A spanner which comprises a handle and jaws, the jaws comprising an upper jaw and a lower jaw, the upper jaw being articulated by means of an upper hinge pin to a distal part of the handle and the lower jaw being articulated by means of a lower hinge pin to the upper jaw, the lower jaw extended by a pawl projecting on the opposite side of the lower hinge pin to the lower jaw, the handle comprising a ratchet tooth which engages with the pawl, in which the upper hinge pin is located near the distal end of the handle and the ratchet tooth is located at an intermediate position between the upper hinge pin and the proximal part of the handle, and in which the ratchet tooth comprises a ramp and a stop, adapted so that rotation of the handle counterclockwise with respect to the upper jaw causes the pawl to ride up the ramp thus closing the jaws until the pawl engages the stop which positively stops further closing of the jaws at a predetermined gap.