Economy Automatic Changeover LPG Regulator feeds from two propane cylinders and automatically switches to the full tank when current tank runs empty. Flag in window changes from green to red and indicates that the tank is empty and needs refilling. The regulator is pressure adjustable. 210,000 BTU output. Inlets = 1/4″ Female inverted thread, Outlet = 3/8 ” Female pipe thread. See Part # RP-24 for inlet pigtails. Perfect for smaller homes and RV’s with small or limited appliances. Use with RP-24 Rubber Pigtails 24″. Needs 2 pieces. One per tank hook-up.