The JR Products Compact Low-Pressure Two-Stage Automatic Changeover LP Gas Regulator automatically redirects LP gas vapor flow from an empty designated service cylinder to a reserve cylinder without interruption.• Compact design• Green indicator dome changes to red when the service cylinder needs to be filled• 1/4" Inverted Flare Inlet Connections• 3/8" FPT Outlet Connection• Zinc Die-Cast• Molded Rubber Diaphragms• UL Approved• 2nd Stage Relief Mechanism Per UL 144• Powder-Coated Green indicator dome changes to red when service cylinder needs to be filled 1/4"" inverted flare inlet / 3/8"" FPT outlet connection UL approved | Jr Products Compact Low-Pressure Two-Stage Automatic Changeover LP Gas Regulator in Red