Cavagna (52-A-890-0006C Auto Changeover Regulator Kit Cavagna AUTOMATIC CHANGEOVER REGULATOR - Kit Includes Mounting Bracket And Plastic Cap Cover Automatically switches from empty service cylinder to full reserve cylinder, ensuring continuous gas flow to appliances Highly visible full/empty indicator signals need for refill Built-in back check valve allows empty cylinder removal and refill as reserve cylinder remains operational Adjustable pressure setting