Black silicon carbide sharpening stone black in color,high hardness,highly brittle,sharp abrasive grain,good heat conductivity Itemfeaturesmain applicationnormal ... black in color,high hardness,highly brittle,sharp abrasive grain,good heat conductivityapply to alloy,optical glass,ceramics, ... silicon carbide sharpening stone2.high quality, better price3.normal grain sizes,12# to 32#,W50,W40,W28...... ETC ...