Those were to be used for interchangeable abrasive pads. One leather strip would be treated with 1.0, another one with 0.5 and the third one with 0.25 micron abrasive. Each would be backed with a magnet and so would the backing. In any case the idea got scrapped, I glued a single strip of leather onto the marble and got some great results with 0.5 micron chromium oxide.