BRK First Alert AC/DC Carbon Monoxide Alarm

Direct wire AC powered with battery backup (2 AA batteries included). Electrochemical CO sensor – most accurate technology available for detecting carbon monoxide as compared to other sensing technologies. Battery backup provides consistent protection for added safety during power outages. Mute button mutes unwanted alarms. Also tests alarm function with the same button. Front-open compartment allows easy battery change without dismounting alarm. End of life signal provides audible confirmation alarm needs to be replaced. Loud 85dB alarm.