The Kidde Smoke Detector & Carbon Monoxide Detector Combo with 10-Year Battery, model P3010K, provides two fire safety detectors in one unit through the use of photoelectric sensing technology that senses visible fire particles, while an electrochemical sensor detects carbon monoxide. When a smoke, fire, or carbon monoxide event occurs, the Kidde fire alarm warns with an 85-decibel alarm sound & a flashing LED. 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. In the case of a nuisance or a false 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. When installed, the green LED on the alarm will flash every 60 seconds in standby condition, letting you know that the unit has power & is operating correctly. 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).