This unit is an AC/DC powered, ionization smoke alarm that operates on 120V power source. This alarm uses ionization sensing technology that may detect invisible particles (associated with flaming fires) sooner than photoelectric alarms. Photoelectric sensing alarms may detect visible particles (associated with smoldering fires) sooner than ionization alarms. This unit includes a quick connect wiring harness for easy installation, is available in 6 piece cut case with tray for easy display, UL listed and has a 10-year limited warranty. 9V Battery back-up.