The First Alert BRK 7010B hardwire photoelectric smoke alarm with battery backup is a hardwire 120V single or multiple station smoke alarm designed for residential home use and institutional locations such as hospitals, hotels, motels, dormitories and other multiple family dwellings. This alarm is inter-connectable and can be installed and linked with up to 18 compatible devices (up to 12 smoke alarms and 6 compatible devices like bells, horns and repeaters) so that when one triggers, all alarms sound. The First Alert BRK 7010B emits loud 85dB audible alarm. The alarm also features a photoelectric smoke sensor, which is particularly effective at detecting slow smoldering fires. The Frist Alert BRK 7010B hardwire smoke alarm with battery backup is packed with convenient features. The single test/silence button silences a non-threatening alarm or low battery warning; plus allows you to test the unit's functionality quickly. The latching alarm indicator will automatically identify which unit initiated the alarm if alarms are installed in a series – helping identify the initial location and source of an incident. The smoke detector also includes an optional drawer and mounting bracket lock to prevent tampering or removal of the 9-volt battery. End of life signal provides audible notice when the alarm needs to be replaced after 10 years of service. This alarm is backed by a 10 year limited warranty and is tested to meet UL standards 217. Includes smoke alarm, mounting bracket, 9-volt backup battery and user's manual.