CO2 CYLINDER SWITCHOVER VALVE This brass switchover device enables you to have (2) CO2 cylinders hooked up to the system. When one tank runs out of CO2, simply turn the blue knob to the other side and open the other CO2 cylinder. This allows you to keep selling your beverages with virtually no down time. The bottom fitting gets hooked up to the system. The (2) side fittings get hooked to the CO2 cylinders. Both CO2 cylinders MUST have regulators on them set at the pressure needed for your carbonator. DO NOT ALLOW GAS INSIDE THE SWITCHOVER UNREGULATED!