The M7 NC-3812B pneumatic impact wrench fastens and removes various bolts of different sizes. This tool is popular among auto mechanics and anyone else who works with nuts and bolts. Its 3/8" square drive has a 1/2” bolt capacity, so keep that in mind when working with the tool's 66-120 ft-lb of torque. The air wrench also has a maximum reverse torque of 180 ft-lb. This tool's compact size and light body weight help reduce user fatigue on longer jobs. Shop JB Tools and get the best price on this M7 NC-3812B 3/8" air impact wrench. This M7 pneumatic impact wrench features a positive clutch mechanism. It connects two rotating shafts with interlocking teeth or “dogs.” This is why this clutch type is also called a “dog clutch” or “twin dog clutch.” These two clutch shafts push against each other and rotate at the same speed. This helps prevent slippage and reduces wear and tear. Positive clutches are not used to control the tool's torque.