1.aluminium oxide,silicon carbide or zirconium oxide 2.resin over resin 3.vulcanized fiber ... Paper Disc:Vulcanized Fiber Disc,1)abrasives:aluminum oxide,silicon carbide,or zirconium oxide;2)mainly used in ship,automobile,aviation ... -120 400 39×39×18 20.00/22.00 silicon carbide Sand Paper Disc