These straight type torque control screwdrivers are excellent for critical fastening applications such as plastics, composites, or metals, where the utmost accurate torque control is required. Additional features include: Less reaction due to the unique clutch mechanism. High torque accuracy for quality control. Quiet operation through muffled rear exhaust. External torque adjustment. The 30 and 40 series have ''oil-free'' rotor blades. Push-to-start-operation. Models listed have a 1/4'' hex bit.