... 4)Backing: Velcro. Velcro Sanding Disc (Suitable for Grinding and Polishing for Automobile)Material: Aluminum oxide, black silicon ... it is easy to be fixed on hard rubber disc of pneumatic or electric tools ... polishing surface . Applications: Mainly grinding and polishing for automobile, paint, wood, stone, metal and so ... is no pollution.Suitable for metal, wood, automobiles, and furniture, especially ...