Features: 1) Combined magnesia with solubility in acid and solubility in water 2) Large hardness 3) Combination proportion adjustable 4) Specifications: a) Grain size: 2.5 - 4.0mm (3), 1.0 - 2.0mm (4) b) Moisture content: less than 2.0% (3) or 5.0% (4) c) Hardness: more than 3.0kg/cm2 (3) d) Disintegrable rate: more than 90% (4) e) C-MgO: more than 55.0% (3) or 40.0% (4) f) W-MgO: more than 10.0% (4) g) W-B2O3: more than 0.2% (4) h) Appearance: white