The Kidde i12060ACA is a 120 VAC, wire in smoke alarm with front loading 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 i12060ACA provides continuous protection against smoke and fire hazards, even during power outages. The front-loading battery door allows user to change the battery without removing the alarm from the mounting bracket making battery replacement easy and convenient. This alarm uses ionization sensing technology. Ionization sensing alarms may detect invisible fire particles (associated with flaming fires) sooner than photoelectric 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.