... ball1mm-60mmPP,PE,ABS,POM,PA,PMMATrackball,Ball valve,Bearing ball, Roll on ball,and so onHollow ball10mm-100mmPP ... diameter 1mm--60mm, mainly used in the industry of bearing.2) Plastic balls are made of different materials, such ... ball1mm-60mmPP,PE,ABS,POM,PA,PMMATrackball,Ball valve,Bearing ball, Roll on ball,and so onHollow ball10mm-100mmPP ... to receiving your order! plastic ball roll in guide rail