First Alert Atom 10-Year Battery Photoelectric Smoke Alarm Atom photoelectric smoke alarm with 10-year battery delivers the same advanced protection as a traditional alarm while taking up only a fraction of the space. Uses an ultra-reliable photoelectric sensor to detect smoke from smoldering fires while keeping false alarms to a minimum. A built-in 10-year lithium-ion battery provides continuous power, with no need to ever worry about changing batteries during the lifetime of the alarm. Much smaller than an ordinary smoke detector, this unit is manufactured using 52 percent less resin and 76 percent less plastic than a standard alarm. The SmartClip mounting system allows for easy installation on a wall or ceiling. A loud 85-decibel siren sounds if smoke is detected, and a convenient test/silence button lets you easily check alarm function and mute false alarms. Type Battery Operated, Voltage 3V, Battery Life 10 Yr. Battery, Sensor Type Photoelectric, Battery Back-up Battery Only, Alarm Type Smoke, Decibel Level 85dB, Battery Type 3V Lithium Battery, Batteries Included Yes, Color White, UL Listed Yes, Warranty 10-Year Limited, Pkg Qty 1, Package Type Clamshell