Abstract: A device for rotating a screw into or out of a workpiece, the device being connectible to a power drill and including a screw driving member. There is provided between the power drill and the screw driving member a mechanism for determining the direction of rotation of the screw-driving member and a torque-adjusting mechanism for controlling the depth a screw is to be driven into a workpiece and including clutch means rotatably associated with the rotational-direction determining mechanism. The rotational-direction determining mechanism comprises a planetary gear system, whereof the planet carrier is adapted to be locked to effect rotation of the screw-driving member in a screw-extraction sense (i.e. reverse rotation) or to be released to effect rotation of the screw-driving member in a screw-insertion sense (i.e. forwards rotation).