... manufacter 5.quick reply Introduction: 20%-80% Alumina Content Porous Ceramic Balls also called filtering balls. It is ... made by make 20~30% pores inside the inert ceramic balls. Therefore it ... are divided into 12 grades by reference to Al2O3 content varied from 25% to 80%, and every more ... as Φ3,Φ6,Φ8,Φ10,Φ13,Φ16,Φ20,Φ25,Φ30,Φ38,Φ50 and Φ75. The products in other grade ...