This automatic changeover regulator switches from an empty tank to the full tank, so there is a continuous gas flow. It is equipped with red and green indicators that let you know the status of the tank the arrow is positioned to. The empty tank can be removed while the other tank is still open, with no interruption in the flow of gas. It is set at a pressure rating of 11″ water column (0.4 psi). Manufactured by Cavagna.