wheel wrench based on the torsion bar principle. which speeds up the tightening of wheel nuts and bolts. The process is automatic. because the shaft part of the wrench twists when the specified torque is reached and the pneumatic wrench does not overtighten the wheel nut or bolt. DIN 3121/ISO 1174. Each wrench is painted in a different color. for faster finding the version with the required torque. For machine use. Chrome-molybdenum.