Abstract: The open-end wrenching head includes two jaws and a throat interconnecting the jaws. The jaws include planar jaw driving surfaces each with a roughened region thereon adjacent to the throat and an unroughened region adjacent to the outermost end of the jaw driving surface, each of the roughened and unroughened regions being constructed and arranged to engage a portion of a selected side of a fastener. The throat may include either an arcuate surface or two planar throat driving surfaces. Each of the roughened regions has a coefficient of friction substantially greater than that of the unroughened regions and may be formed by deposition of an abrasive material by any of a number of processes or by deformation of the jaw driving surface by any of a number of processes.

Abstract: The open-end wrenching head includes two jaws and a throat interconnecting the jaws. The jaws include planar jaw driving surfaces each with at least one serrated region thereon constructed and arranged to engage a portion of a selected side of a fastener. The throat may include either an arcuate surface or two planar throat driving surfaces having serrated regions thereon. Each of the serrated regions on the driving surfaces may include symmetrical or asymmetrical grooves. The plane of these grooves may be parallel to the driving surfaces or at an angle of about 1.degree. to 3.degree..