The SP range of Measuring Tools aremore than just functional. They aredurable and finished with attention to detail. Alloy and steel surfaces have been treated to create a finish that is resistant to oxidation and wear All torque wrenches are calibrated and tested. The SP range of Torque Wrenches are calibrated and tested ex-factory to have a minimum degree of accuracy of + 4%. As such, torque wrenches are a precision measuring instrument and should be stored and used with this in mind. SP suggests the following instructions be followed to maintain the torque wrench. Have torque wrench re-calibrated by a trained professional at least once a year.