Totally eliminate confusion with this exlusive smart combo alarm. The voice system states one of three messages including: Warning Carbon Monoxide Fire Fire or Low Battery, plus an ultra loud 85 decibel alarm alerts you to smoke/fire or carbon monoxide danger at the same time. In addition, the alarm warns you if CO levels were detected while you were away. as well as a blinking light that indicates low battery condition. The advanced CO and Smoke Sensor make you aware of danger immediately. It's easy to install in any room of your home with no wiring required. 10 year limited Mfg warranty on smoke and CO alarm. Battery operated. Requires 2 AA batteries included.