Interconnects up to 24 Kidde devices (of which 18 can be initiating)|Battery provides protection during power outages|Front loading battery door replace the backup batteries without disconnecting from mounting bracket|The battery door will not close unless the batteries are properly installed|Alarm tamper-resist helps deter from tampering and theft|Adjustable mounting bracket, makes installation fast and easy, works with existing smoke and combination smoke and carbon monoxide mounting brackets|Peak level memory announces carbon monoxide previously DETECTED if alarm has detected a carbon monoxide level of 100 ppm or higher since it was last reset|Hush silences nuisance alarms for approximately 9 min|Ionization sensor technology for detecting fast flaming and other types of fires|Tests the unit for proper operation, peak level memory, resets the carbon monoxide alarm|Green LED illuminates to indicate the unit is receiving AC power flashes once every 60 s to indicate battery only mode, flashes once per second during alarm to indicate initiating alarm, flashes once every 16 s to indicate smoke or carbon monoxide previously detected, flashes every 2 s while the alarm is in Hush mode|When a dangerous level of smoke or carbon monoxide is detected the red led will flash if the unit malfunctions, the red led will flash and the unit will chirp every 30 s