The Kidde Firex Battery Powered Combination Smoke & Carbon Monoxide Detector with Voice Alerts, model 900-CUDR-V, is an alarm combo that operates on 2 AA batteries (included). Battery-operated smoke detectors protect during power failures for extra peace of mind. If the smoke & carbon monoxide alarm detects smoke, fire, or carbon monoxide, an 85-decible alarm & voice alert will sound stating, "Fire! Fire!" or "Warning: Carbon Monoxide." The combination smoke & carbon monoxide detector also provides a voice alert of "Low Battery" when the battery on the unit needs to be replaced. The Kidde Smoke & Carbon Monoxide alarm uses photoelectric sensors that detect visible fire particles associated with slow smoldering fires, as well as an electrochemical carbon monoxide sensor, which offers highly accurate readings of CO. Carbon monoxide alarms help protect your family from the dangers of carbon monoxide - a poisonous, odorless gas. The alarm will also begin to chirp when the battery is nearing the end of its life & needs to be replaced. When a nuisance or false alarm sounds from routine cooking or shower steam, the Hush feature temporarily silences the Kidde combination smoke & carbon monoxide detector. Install a smoke detector and carbon monoxide detector on each level of your home, in hallways and inside each bedroom. UL Certified with a 10-year limited warranty. Meets requirements of UL 2034, UL217, NFPA72, NFPA 101, FHA, & HUD.