For 1 1/2" to 3 1/8" Disc Brake Cylinders (38.1 to 79.3mm). Special abrasive pads polish the cylinder without cutting. Controlled pressure, three abrasives and flexible driver give good stability and speed. Stones are 1" long. - 10490 replacement stones (green rubber) - Ends are 1" long - 400 grit - 10120- Replacement O-Ring * 3 arms- needs 3 stones * Stones are held on to tool by a rivet when original tool goes out * Replacement stones use a cotter key * Stones are interchangable.