2-in-1 combination smoke and carbon monoxide alarm with photoelectric smoke sensor and patented smoke entry system which reduces false alarms. Slim design is half the size of a standard alarm with nuisance free technology. Features test/silence button and end of life signal. Easy to install wall or ceiling mount with simple slide-in mounting bracket. (2) AA batteries included. Battery life varies according to use and application. 7-year limited warranty. ETL listed.