Abstract: An open end C-wrench is provided having an open end C-wrench head driven by a conventional square ratchet extension tool. The open end C-wrench head has four flat surfaced jaws encompassed within a thin, narrow web body having a small square hole integrally centered therein. The jaws include two opposed unequal length, one short and one long, parallel drive jaws enclosing two adjoining equal length backup jaws. The four jaws squarely engage four continuous sides of the nut defined first, second, and third and fourth sides. When the wrench is in the drive position, the short drive jaw surface engages about fifty percent of the first side of the nut while the longer drive jaw engages about ninety percent of the fourth side of the nut while the two backup jaws coextend in secure engagement with the second and third sides of the nut. Greater driving torque is provided by the drive hole being integrally centered in the web body.