Diameter mm 13 Height mm 10 Thickness mm 2~2.5 Bulk density kg/m3 750 Free volume % 65~68 Surface area m2/m3 600 Specific gravity g/cm3 2.25~2.35 Water absorption % <1.5 Acid resistance % >98 Max operating temp. °C 1300 Moh's hardness Scale 6.5~8