PU Roller with double bearingsAll roller diameter 30mm,Roller size 30m.According to bearing bore. there are bearing bore 5mm,6mm,8mm,10mm.Bore 5mm with 2pcs 635 Bearings.Bore 6mm with 2pcs 626 Bearings.Bore 8mm with 2pcs 698 Bearing.Bore 10mm with 2pcs 6800 Bearing.Please select "Color Item" you need, I will put up per your order.Material: PUWidely utilized in elevators, medical equipment, conveyor belt, sliding doorways and windows, machinery and equipment