The Kidde Smoke & Carbon Monoxide Detector, 10-Year Battery, Voice Alerts, model p3010cu, provides two fire safety detectors in one unit through the use of photoelectric sensing technology that senses visible fire particles (associated with smoldering fires), while an electrochemical sensor detects carbon monoxide. The Kidde combination smoke and carbon monoxide alarm is powered by a 10-year lithium battery, which eliminates the need for battery replacement, while providing coverage during a power failure When a smoke, fire, or carbon monoxide event occurs, the Kidde fire alarm warns with an 85-decibel alarm sound, flashing red LEDs, and voice alerts announcing, ''Fire! Fire!''. For carbon monoxide detection, the alarm will sound with the announcement ''Warning! Carbon Monoxide!''. When the smoke alarm is at the end of its life span, the detector will announce, ''Replace Alarm!'' . The Smart-Hush button silences the unit for approximately 8 minutes, which is helpful when this smoke detector carbon monoxide detector combo sounds from things like routine cooking or shower steam. Install a carbon monoxide smoke detector combo on every level of your home and near bedrooms to help keep your family safe. UL Certified with a 10-year limited manufacturer's warranty. Meets requirements of UL 2034, UL217, NFPA72, (chapter 11 2002 edition) The State of California Fire Marshal, NFPA101 (One and two family dwellings) Federal Housing Authority (FHA), Housing and Urban Development (HUD).