JS-M9 is moisture-proof and high temperture resustant magnesium oxideGRADE Aused for medium and low temperature air heating elementsisnt suitable for high-heat treatmentìsuch as 1050C annealingit has high moisture proof propertysimply sealing is available. We syggest to dry the heating elements at 200C-350C before sealing. 25KGS/BOX OR 25KGS/BAG