The non-electronic cylinder holder attaches to the left side of the Galaxy GX2 docking station. It allows the gas in your cylinder of gas to travel (via a demand flow regulator) MSA part # 10034391 to each one of your docking stations. MSA GX2 Galaxy Docking stations and regulators sold seperately. Cylinder Holders sold EA.
See TnA Safety, Webster, NY on MacRae's Blue Book