twin wheels medical caster,twin wheels chair casters,twin wheels hospital chair casters Wheel Material:TPR,PA Size:3\" x 56mm ; 4\" x 56mm ; 5\" x 80mm Loading Capacity:60kg-120kg Bearing Type:Delrin Bearing Type Optional: Plate Swivel,Thread Swivel,Stem Swivel Widely used as hospital bed caster,Medical trolley caster www.casterwheelsco.com