... bearing.2) Plastic balls are made of different materials, such as PP,PE, POM, PA,PMMA ... HDPE and so onUsage:for ball bearing,cosmetic package,industrial ,track ball,and so on hollow ballsize ... Usage:floating ball,valve ball,sewage ball,cosmetic package,industrial ,track ball,and so on plastic ... 50ml,60ml,75ml PP,HDPE,PE cosmetic packagepharmaceutical package glass roll on bottle25ml,30ml,45ml,50ml,75ml ...