guide ball cage *Certificates:ISO9001 *Material:Bronze,Aluminium,POM; *Size:Customized; *low friction coefficient guide ball cageBest in quality linear ... can made of other material ,just like ceramic,plastic etc.)NO 1: Plastic bushing (blue,white colour,POMS,POMBS,POMM,POMBM,POMT ... glad to give you the best service. different model of big size ball bearing