The CMD-4MR-RLY is the most advanced CO detector available from Fireboy-Xintex. It features automatic generator shutdown capability. When dangerous CO levels are detected, the CMD-4MR-RLY shuts down the generator, a common source of CO. This detector also features multiple location warning, allowing up to six detectors to be linked in series. When one detector alarms, all connected detectors will alarm to alert boat inhabitants in other locations to the presence of CO. Features a state-of-the-art sensor that is unaffected by common cleaning solvents. 12 VDC operation. Low current draw. UL 2034 Listed for Marine use.