The Kidde Smoke Detector with Indoor Air Quality Monitor, Hardwired with Smart Features and Voice Alert, model P4010ACSAQ-WF, is an industry first: a hardwired smoke alarm and indoor air quality monitor combo. Using photoelectric sensor technology, the Kidde smoke, and indoor air quality alarm will detect visible fire particles, associated with slow smoldering fires, and alert you by sounding an 85-decibel alarm & announcing "Fire! Fire!". The Kidde smoke alarm connects to 120V AC power & has a lithium battery backup in case of power failure, providing continuous protection throughout the 10-year life of the alarm with the benefit of never having to change a battery! Provides real-time detection information for air quality & provides a means to set up alerts for family & friends - even the pet sitter - to alert to a potentially dangerous situation in your home. An LED ring-light indicator alerts you to the various state of the alarm: green = normal operation, amber = operating error, and red = a smoke or fire hazard. A Test-Hush button activates the Hush feature to temporarily silence nuisance alarms & test the unit. Capable of whole-home activation with select Kidde alarms that have hardwired AC interconnect capability (see User Guide), so when one alarm sounds, they all do. UL Certified with a 10-year limited warranty (not a battery performance claim).