The Kidde 900-0120 is an AC wire-in carbon monoxide alarm that warns you and your family of dangerous carbon monoxide levels. It includes multiple contractor friendly features to ensure easy installation and minimal troubleshooting. This alarm interconnects with up to 24 Kidde devices (of which 18 can be initiation) including smoke alarms, carbon monoxide alarms and heat alarms on one wiring network. The 900-0120 includes a 9 VDC battery backup along with a 5 years limited warranty.