The Kidde i12010SCA is an AC/DC powered, ionization smoke alarm that operates on a 120 V power source with sealed-in lithium battery backup. This alarm uses ionization sensing technology. Ionization sensing alarms may detect invisible fire particles (associated with flaming fires) sooner than photoelectric alarms. Photoelectric sensing alarms may detect visible particles (associated with smoldering fires) sooner than ionization alarms. Leading authorities recommend that both ionization and photoelectric smoke alarms be installed to help insure maximum detection of the various types of fires that can occur within the home. The i12010SCA contains a 10 year tamper-proof battery that eliminates the need for battery replacement and ends worry over unauthorized battery removal. The alarm provides continuous protection from smoke and fire, even during power outages. At the end of alarm life, the unit will chirp, indicating the alarm is in need of replacement. The customer can use a simple tool such as a screwdriver to deactivate the unit, stopping the chirp and making it safe for disposal. The end of life signal can be temporarily silenced to allow for replacement at a more convenient time. Temporarily silences nuisance alarms for approximately 9 minutes 120 V Interconnectable - will interconnect with up to 24 other devices (18 of which can be initiating) 10 years sealed lithium battery backup - no battery to replace for the life of the alarm (10 years) Hush® feature - temporarily silences nuisance alarms Simultaneously tests the unit's electronics and verifies alarm operation