2~4mm Activated Alumina Ball 1)The best choice for sapphire grower 2) ... :powder and ball3)Passes ISO9001:20082~4mmActivated Alumina Ball2~4mm Activated alumina ball has much micro-paths, so the specific surface ... strong for water, oxide, acetic acid, alkali etc. 2~4mm Activated alumina ball defluorinated just as the anion exchange resin, but ...