FRST ALRT SMOKECRBN ALR Smoke alarms save lives each and every day. They help provide early warning for deadly fire danger. The First Alert SCO7CN uses photoelectric smoke sensing technology for optimal protection from smoldering fires and reduced false alarms. An electrochemical sensor offers the most accurate technology available for detecting carbon monoxide. When the alarm sounds an actual voice speaks the type and location of danger in your home. Plus, the remote mute feature allows you to use the Volume and Channel buttons on most IR remotes to mute the alarm from up to 20ft. away. Two "AA" batteries are included.