... caster 2.Wheel diameter: 75mm,100mm, 125mm3.Caster material: Hard rubber with delrin bearing,pressed steel,zinc plated,double ballrace swivel ... . Our wheel diameter is from 15mm to 300mm, materials include rubber, TPR, PU, plastic, nylon, cast iron, pneumatic, phenolic and sandwich ... about us!3.Similar Product4. Factory 65 American type hard rubber ball caster threaded stem side brake caster