Easily replace the 2 AA batteries without disconnecting from mounting bracket. This alarm model also includes a safety feature in the battery safeguard – The battery door will not close unless the batteries are properly installed. There’s nothing more important than keeping your family and home safe, and when fires are a very common type of emergency a homeowner can face, you want to be prepared. The Kidde KN-COSM-BA combination Fire Detector and Carbon Monoxide Detector pairs two life saving devices into one unit. It uses an ionization sensor and electrochemical sensor to monitor your home for potential hazards, so you will always feel safe and confident. Voice alarms along with chirps indicate the hazard that has been detected for fast response. Alarms include: > Fire: The red LED will flash along with three long beeps, followed by the message “Fire!” > Carbon Monoxide: Four short beeps followed by the message “Warning! Carbon Monoxide!” Kidde 21026043 Battery-Operated (Not Hardwired) Combination Smoke/Carbon Monoxide Alarm with Voice Warning KN-COSM-BA. Interconnects - No.