this kind of cutting sand disc mainly use in air tools or power tools, for grinding metak. the material is aluminum oxide. Sand disc Specifications1) Sizes: 4", 4.5", 5", 6", 7" 2) Fiber thick: 0.6, 0.7, 0.8mm 3) Grain: alumina, silicon carbide, zirconia 4) Grit: 16-400Features: 1) Sizes: 100X16mm, 115X22mm, 125X22mm, 150X22mm, 180X22mm2) Coated grain: aluminium oxide, silicon carbide, zirconia ...