... rubber with delrin bearing,pressed steel,zinc plated,double ballrace swivel head, transparent dustproof seal4.Chrome, zinc or nickel plating available ... 5.Matches with different fittings such as swivel, fixed , double brake ,threaded stem and solid stem 6.Plastic,thermoplastic and Polyurethane is ... .Similar Product4. Factory 65 American type hard rubber threaded stem swivel stroller caster