Index Specificatiom Crystalline Phase χ­-ρ Al2O3 Sphere Size mm Φ 3--5 Φ 4--6 Φ 5--7 Appearance White Sphere Bulk Density g/cm3 0.68--0.75 0.65--0.72 0.62--0.68 Crush Resistance N/sphere ≥ 120 ≥130 ≥150 Surface Area m2/g 300--360 Pore Volume cm3/g 0.38--0.42 Coefficient Of Water Absorption % ≥50 Static Absorbing rh% 17±1