Full 2ins to 7ins Range (50.8 - 177.8mm). Controlled pressure assures positive, adjustable contact through full range. Operates with any electric drill. Furnished with 3ins long 220 grit stones, see below for other grits. Adjustable stop collar permits quick selection of two range settings, from 2ins to 4ins and from 4ins to 7ins. Stone arms are easily compressed to eliminate cylinder scratches