The TEKTON 3-pieces 1/4, 3/8, 1/2 in. Drive Micrometer Torque Wrench Set lets you confidently tighten fasteners to precise specifications, ensuring parts are properly secured without being damaged. Simple and easy to use, these wrenches have reversible ratcheting heads that drive fasteners in both directions and measure torque in the clockwise direction. To measure torque, set the desired value on the handle scale and begin tightening the fastener. When the preset torque value is reached, a reliable mechanical operation inside the handle produces a click you can hear and feel, alerting you to stop applying force. These wrenches are shipped pre-calibrated and ready to use. To help maintain calibration, store the torque wrenches at their lowest torque settings when not in use. Material: Steel.