Kidde i9050 is powered by a 9-Volt battery, providing continuous protection even during power outages. Unit includes a flashing red LED to indicate the alarm is receiving power. The alarm uses ionisation sensing technology. Ionisation sensing alarms may detect invisible fire particles (associated with flaming fires) sooner than photoelectric sensing alarms. Unit is a full size, smoke alarm providing you and your family an early warning signal against the dangers of fire and smoke, easy to instal - no wiring needed Kidde i9050 includes a test button to verify the unit's electronic circuitry, horn and battery function are working properly Includes a tamper resist feature to help deter theft or tampering Flashing LED indicates alarm is receiving power, 9-Volt battery included (21025830) Style: Standard Packaging Colour: White Smoke 44037402