Pro-Grade wrenches are built to stand up to the toughest work conditions. Combinations Open End and Flare Nut styles are hot drop-forges from chrome vanadium alloy then heat treated for optimum strength. Box ends are precision broached and chamfered for a smooth secure fit and featured the Dyne-Drive Torque System which dramatically improves performance when compared to conventional wrench driving systems. The board flat paneled beams are smooth edged then nickel-chrome plated and polished to a mirror finish. This allows the application of up to 20% more driving torque with no slippages or fastener damage. In addition many fasteners with existing rounded corners can now be worked more easily. The results are wrench sets that instantly convey a message of exceptional quality and workmanship.