Wera Tools - Safe-Torque A 1 SHK Set 1, 1/4" square head, 2-12 Nm20 piece set in a robust textile box, especially for HVAC applications. One Safe Torque A 1 torque wrench with 1 4"" square head drive, 2 12 Nm, with slide over mechanism. Once the set torque has been reached, the tool cannot be overtightened, so that excessive torque cannot be applied. Setting range of 2 to 12 Nm for controlled clockwise and counterclockwise torque operation. Easy setting and saving of the default value: The audible and tactile