... tanks,large degree of redution of acid mist,carbon dioxide and oxygen in the air pollution of water,to protect water quality ... ,POM,PA,PMMATrackball,Ball valve,Bearing ball, Roll on ball,and so onHollow ball10mm-100mmPP,PE,HDPERoll on ball,Bearing ball ... ,Ball valve,Floating ball,and so onRoll on ball and holder8mm, 10mm,19.05mm,25.2mm,25.4mm ...