The SMICO105-AC Interconnect Smoke and CO Alarm with 10-year battery backup provides reliable 2-in-1 protection with superior features. The combo detector can stand alone or be interconnected with other compatible alarms to create an alarm system throughout your home. When one hardwired detector sounds, all connected alarms will sound to help provide an early warning to a fire or carbon monoxide emergency. Integrate with up to 12 other First Alert or BRK Detectors and 6 other compatible devices.