The model MEGR-253 Auto changeover regulator automatically redirects lP gas vapor flow from an empty service cylinder to a reserve cylinder, without interruption of service. It features an easy to read green indicator which changes to red when the service cylinder needs to be refilled. The MEGR-253 Series meet UL, RVIA and NFPA requirements. Inv. Flare Inlet x 3/8" FPT Outlet.