... 9" 4)Backing: Velcro. Velcro Sanding Disc (Suitable for Grinding and Polishing for Automobile)Material: Aluminum oxide, black silicon carbide, zinc-striate ... polishing surface . Applications: Mainly grinding and polishing for automobile, paint, wood, stone, metal and so on .Velcro disc with holes is ... be harmed and there is no pollution.Suitable for metal, wood, automobiles, and furniture, especially ...