First Alert® Plug-in Carbon Monoxide Alarm Plugs Into 120V AC Outlet And A 9V Battery Backup Provides Consistent Protection During Power Outage. Mute button Silence Unwanted Alarms Immediately And Also Tests Alarm Function. Low Battery Beeping Signal Warns When Battery Needs Replacing. Audible End-Of-Life Notice When It Is Time To Replace The Alarm. Loud 85dB Alarm. 

▪ Plug-In Carbon Monoxide (CO) Alarm With 9V Battery Backup
▪ Electrochemical CO Sensor
▪ Single Test/Silence Button
▪ End-Of-Life Signal (CO)
▪  7-Year Limited Warranty
▪ Mfg #CO605A (1039731)