Twin wheels medical caster black color,dual wheels medical casters Wheel Material:PU,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, stretcher caster,Laboratory Casters,healthcare bed casters