The final fastening torque Auto Shut off Air Screwdriver is set by adjusting the compression of a clutch spring within the front section of the tool. This class of Auto Shut off Air Screwdrivers tool is recommended for hard or soft joints or for self-tapping or sheet metal screws provided tapping torque does not exceed the final torque. Automatic shut-off tools also reduce air consumption and are the most ergonomically sound of all air screwdrivers.