Protect your family, home or business from smoke or fire when you install the Kidde P9050 Photoelectric Smoke Alarm. Powered by a 9-Volt battery, this alarm uses photoelectric sensing technology to detect visible incendiary particles associated with smoldering fires. Simply push and hold the alarm's test button to check its circuitry, horn and battery function. A low-battery indicator sounds a chirp alert when the battery runs low. This unit mounts easily, thanks to its wireless design.