With electrochemical sensing technology and a clear loud alarm, the FA6813 provides trusted carbon monoxide (CO) detection for your home. The alarm comes with 2 x AA batteries that can be replaced once you hear the low battery chirp to keep you protected. For a decade of protection look for our range for FireAngel Pro Connected alarms. Enjoy a peaceful night’s sleep. Give yourself vital time to replace your alarm, by silencing low battery warnings for 8 hours. Alarm memory indicates previous activation: With the alarm memory function, a red LED will flash to let you know with a visual indication that there has been a previous CO alarm activation within the last 30 days.