ball bearing dual wheels caster,Twin wheels hospital bed casters with brake,Twin wheels medical caster with brake Wheel Material:PU,PA Size:3\" x 56mm ; 4\" x 56mm ; 5\" x 80mm Loading Capacity:60kg-120kg Solid stem size: 28mm D x 40mm L 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,medical devices casters www.casterwheelsco.com