... is also called filtering balls. It is made by make 20-30% pores inside the inert ceramic balls. Therefore it can ... ≥90Fe2O3≤1 Pore size,um0.5-3540-100110-1000 Porosity,%20-3015-2515-25 Air permeability,m3·cm/m2·h·10Pa0 ... as Φ3 ,Φ6 ,Φ8 ,Φ10 ,Φ13, Φ16 ,Φ20 ,Φ25 ,Φ30 ,Φ38 ,Φ50, Φ75. The products in other grade and sizes can be ...