Abstract: The present invention is comprised of a handle having an enlarged head at one end with a cylindrical bore passing through it. A drive element rotatably located in the bore has three equally spaced planar cam faces which are separated by circular segments having a radius approximately equal to the radius of the bore. Elongate rollers which fit in the three semi-cylindrical portions of the bore remaining between the drive element and the periphery of the bore, have diameters which are approximately 0.002 less than the maximum distance between the cam faces and the periphery of the bore. A selector rotatably attached to the drive element has three pairs of prongs with one of the prongs in each pair being located on each side of a roller. A detent which is operative between the drive element and the selector causes the rollers to be completely wedged between the cam faces and the periphery of the bore when the selector head is rotated to either side of center and locks them in this wedged position during use.