[Two-Stage Automatic Conversion Propane Gas Regulator]This two-stage regulator can be connected to two propane tanks. It allows empty tanks to be removed and refilled without interrupting the propane supply. For RVs with dual propane tanks, when the primary tank is empty, it automatically switches to the backup tank and the indicator light changes color to let you know the tank is depleted and needs to be replenished. [Specifications]RV Propane Regulator: Main tank capacity 210,000 BTU/hour, backup tank capacity 130,000 BTU/hour. Inlet is 1/4inch SAE reverse flare and outlet is 3/8inch female NPT. RV Pigtailed Propane Hose: 1/4inch inverted flare fitting and QCC1 connector (not 1/4inch NPT threaded). If you order, please check your connector before use [2-Pack 18-Inch Metal Braided 1/4-Inch Inverted Flared RV Pigtailed Propane Hose with Pressure Gauge]1/4-Inch Inverted External Flared Metal Braided RV Propane Pigtailed Hose to 1/4-Inch Inverted External . (Not 1/4inch male NPT. Please