The First Alert P1210E 10-year battery photoelectric smoke alarm, slim profile with escape light helps protect your home by providing up to a decade of uninterrupted monitoring. This low-profile smoke alarm uses an ultra-reliable photoelectric sensor to detect 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-year lithium-ion battery provides continuous power, with no need to ever worry about changing the battery over the lifetime of the smoke detector. 10-Year lithium-ion battery lasts for the life of the alarm Escape light activates when alarm sounds, helping to light a path to safety Slim shape is half the size of a standard smoke alarm Photoelectric sensor detects smoke while minimizing false alarms Patented smoke entry system allows for a direct path to the photoelectric smoke Features loud 85-decibel alarm and single test/silence button Meets UL217 standards and complies with legislative requirements for 10-year battery operated smoke alarms Smoke and CO alarms should be placed on every level and in every bedroom of the home