Double-Duty Alarm. Detects both gas leaks and CO gas simultaneously12 Volt power means no missing or dead batteries to replaceBuilt for the extreme RV environmentFully operational during mute cycle and will re-alarm if hazardous conditions recurMeets RVIA/NFPA requirementsConforms to UL 1484 RV and UL 2034 RVUpgrades single 12 Volt Propane Gas alarms to a dual alarm that detects both Propane Gas and COModel 35-742 flush mount can replace Safe-T-Alert LP Gas alarm 30-442 models and CCI Controls models 7770 & 7773 without modifications