The Kidde i12040CA is a 120 V AC, wire-in smoke alarm with 9 V battery backup that can function as a stand alone unit or interconnect with up to 24 Kidde devices (of which 18 can be initiating). The Kidde i12040CA provides continuous protection against smoke and fire hazards, even during power outages.

This smoke alarm uses ionization sensing technology. Ionization sensing alarms may detect invisible fire particles (associated with fast flaming fires) sooner than photoelectric alarms. Photoelectric sensing alarms may detect visible fire particles (associated with slow smouldering fires) sooner than ionization alarms. Leading authorities recommend that both ionization and photoelectric smoke alarms be installed to help ensure maximum detection of the various types of fires that can occur within the home.