Sturdy black rubber backing for just the right thickness, robust aluminum core with removable nickel-plated steel shank for added strength The 2-inch diameter grinding disc backing for polishing wheels can be used on any rotary drill or chuck tool Rated at 28,000 RPM, the 6.35mm (1/4") shank is suitable for electric drills, grinders, and pneumatic grinders for any surface polishing/buffing job An ingenious tool for sanding, grinding, polishing, surface conditioning/preparation, paint removal, sanding primers, etc. The discs have a small threaded shank attached to the back of the pad that screws into the rubber pad adapter for mounting