This smoke and carbon monoxide alarm has long-lasting sensors and components that deliver a long life of up to 10 years; also includes a replaceable 3-year lithium battery Informative LCD shows real-time CO concentrations and battery power to monitor for CO leaks and battery level; to save power, it will activate only when the device is tested or the ppm has reached the alarm level for a certain period Featuring a light and thin design, this combination smoke and carbon monoxide detector has a 215430 sq. ft (2040 m) detection range, fully protecting you and your family from dangerous smoke and carbon monoxide This smoke and carbon monoxide detector is built with both a cutting-edge photoelectric smoke sensor and electrochemical CO sensor to deliver high consistency and reliability for double detection and protection The loud alarm tone is over 85 dB at 10 ft (3 m) to alert anyone in a deep sleep; with included screws and anchor plugs, this battery-operated unit can be installed effortlessly without an electrician