The Kidde P9050 is a battery operated smoke alarm, equipped with a photoelectric sensor, designed to alert you and your family to the dangers of smoke and fire. The P9050 includes a 9V battery, providing you protection even during a power failure. This unit is UL Listed and offers a 10-year limited warranty. This alarm uses photoelectric sensing technology. Photoelectric sensing alarms may detect visible particles (associated with smoldering fires) sooner than ionization alarms. Ionization sensing alarms may detect invisible fire particles (associated with flaming fires) sooner that photoelectric alarms. Kidde strongly recommends that both ionization and photoelectric smoke alarms be installed to help insure maximum detection of the various types of fire that can occur within the home. The Kidde P9050 photoelectric smoke alarm is battery operated protecting you and your family even during power outages. This unit does not require any wiring and can be installed in minutes. The P9050 is equipped with a test button that allows you to test the alarm’s electronic circuitry, horn and battery function.