First Alert 1039868 Smoke and Carbon Monoxide Alarm, 85 dB, Alarm: Audible, Electrochemical, Photoelectric Sensor

The First Alert PRC710 slim photoelectric smoke and carbon monoxide alarm with ten year battery helps protect your home from two potentially deadly threats by providing up to a decade of uninterrupted monitoring. Equipped with dual sensors, this low-profile alarm detects smoke from slow-burning, smoldering fires. Half as thick as a standard alarm, this detector has a slim, contemporary design that mounts unobtrusively on a wall or ceiling. A built-in 10 years lithium-ion battery provides continuous power, with no need to ever worry about changing the battery during the lifetime of the alarm.