These industrial pneumatic casters feature air filled pneumatic wheels. These industrial casters are designed for low speed manually moved applications only. Air filled pneumatic wheels provide a cushioned ride, shock absorption and quiet operation. Pneumatic casters are ideally suited for moving fragile or delicate cargo where caster overall height is not critical. Casters with pneumatic wheels are usually the best choice for use outdoors over rough surfaces ( i.e. gravel ) or on grass. The wide footprint on 8″ or larger pneumatic wheels provides stability on gravel and does not sink into lawns.