Atom Photoelectric Smoke And Fire Alarm The First Alert P1000 Atom Smoke and Fire Alarm provides maximum protection and has a new thinner, micro design, which adds an element of style to safety. This photoelectric alarm is a fraction of the size of a standard alarm and provides all the necessary protection to help keep your family and your home safe. This unit has an advanced smoke entry system with a photoelectric sensor that will detect regular and slow, smoldering fires and reduce false alarms that result from cooking and shower steam. The Atom has a loud 85dB penetrating and powerful siren to ensure everyone is out of the building safely. During an alarm, you will hear a loud; repeating horn pattern and an LED light will flash rapidly.The Atom has easy installation with their smart product clip system to attach to any wall or ceiling. This white smoke and fire alarm is powered by (1) 3-Volt CR2-Lithium Battery (included), measures 7.19-inches high with a 2.5-inch radius and weighs only 0.18-pounds. The First Alert P1000 Atom Battery Powered Micro Design Smoke and Fire Alarm comes with a 10-year limited warranty that protects against defects in material and workmanship.