An original model-6 Aladdin hanging lamp with metal chimney tube. The glass chimney fits inside the metal chimney tube, both to protect it from breakage, and to help diffuse the heat produced by the lamp when lit. The metal chimney tube is composed of two layers of metal. The inner tube is often plagued with corrosion, and it can be hard to find one in which both the metal tubes are in good condition.

Both the model-5 and model-6 hanging lamps were offered with or without the chimney tubes, so if you should find one without the metal tube, in reality it is probably not missing the tube, but rather was produced without one.