• The First Alert Atom is protection at its finest. Its micro design 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. • Advanced Micro Technology • Maximum Protection - Fewer false alarms from shower steam and cooking smoke • Photoelectric Sensor - detects slow smoldering fires • Long-life Lithium Battery • Easy Installation - Smart Product Clip System • Loud and Powerful Penetrating Sound