Discs have an Aluminum Oxide, non loading stearate with resin over resin bond for consistent reduction of abrasive grain. The semi open coat and stearate resin are used to reduce clogging. The heavy duty backing on the discs makes this suitable for sanding and stripping paints, pigmented lacquers, primers, sealers, and acid cured lacquers. To use, simply remove the backing, than stick self-adhesive disc to appropriate backup pad attached to orbital sander. All new, sealed and packaged.