[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 QCC 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 swell. (Not 1/4inch male NPT. Please check your connector before ordering.) This propane tank hose comes with a tank level indicator with 3 different color dial gauges for use in the dark Illuminated, allowing you to disassemble and detect leaks without reading and monitoring tank levels [Advanced Design]This propane gas regulator is equipped with a regulator switchable pointer and the propane tank hose is equipped with a tank level indicator with three different color dials that glow in the dark. [Application Scenario] Suitable for RV/camper/travel trailer. These 18-inch RV pigtail propane hoses feature a 2-stage propane regulator that allows you to connect two 5-40 lb. refillable propane tanks or LP gas tanks to your camper's 1/4-inch inverted male torch. Replace any existing automatic transfer regulator in your current RV, travel trailer, camper to maintain constant continuous gas. <br /