Full 2 to 7 range (50.8-177.8 mm). Controlled pressure assures positive, adjustable contact through full range. Three large stones provide more cutting surface and assures quick removal of cylinder glaze. Adjustable stop-collar permits quick selection of two range settings, from 2 to 4 and from 4 to 7 , and serves as safety stop if tool is extracted from cylinder while turning. Operates with any electric drill. Easily compressed with one hand to eliminate vertical scratches which might spoil the diamond cross-hatch pattern when removing tool from cylinder. Furnished with 220 grit stones.