... use dc power supply, working voltage 24 v, have automatic decommissioning functions, namely and common screwdriver power can ... reach hundreds of thousands of times1.Fully Automatic,no carbon brush 2.Little noise,permanent life ... .* Easy to switch working.directly switching from power source.* The speed with HI/LO switch two ... 06 802 Precision Torque Semi-Automatic Electric Screwdriver (power tool,drill)