The First Alert Plug-in Carbon Monoxide Alarm has a battery operated backup. It easily plugs into any standard outlet with no additional mounting necessary. Battery operated backup ensures alarm works even during power outages. Mute button silences any nuisance alarms. Single button also tests alarm functions. Utilizes electrochemical sensor for increased accuracy. 7-year limited warranty. Meets UL standards. | First Alert Plug-In Carbon Monoxide Alarm with Battery Backup