Packing all of the power of an advanced photoelectric smoke alarm into a miniature design, the First Alert P1000 Atom Smoke and Fire Alarm provides maximum protection while showcasing an entirely new micro design that 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.