1.aluminium oxide,silicon carbide or zirconium oxide 2.resin over resin 3.vulcanized fiber Fiber Sanding Paper ... Disc:Vulcanized Fiber Disc,1)abrasives:aluminum oxide,silicon carbide,or zirconium oxide;2)mainly used in ship,automobile,aviation,machinery ... ,bridge,building,and etc.3)ideal for removing rust,paint,deburring and polishing ...