... MgO,MgCl2,Fiberglass mesh We offer Grade A without sanded magnesium oxide board also: ALL LEVELS OF MGO BOARD TABLENOLevelComparison itemGRADE ... with sandedGRADE A without sandedGRADE BGRADE C1magnesium board compositionMagnesium oxide (activity 85%), magnesium sulfate, wood chips, silicon carbide, ... life 50 years10 years1 year1 month Fiberglass board,magnesium oxide fireproof board,fireproof insulation ...