CMD6-MD-BR CO Alarm 12/24V DC - BlackFeatures:CMD6 use the same housings, mounting bracket, and wire connections as CMD5CMD6-MB battery model will be 100% powered by the permanent internal batteries and needs no external powerCMD6-MD 12/24V DC model uses boat power and has permanent internal backup batteries if the boat power goes outNo boat/RV battery draw, no circuit breaker, no wires to run, and much less labor to installOnly battery-powered marine CO Alarm on the market“R” version that will include an internal relay AND the “Interconnect” function