Product details:

Combination Smoke & Carbon Monoxide Detectors by Kidde. Details:The Kidde Hardwired Smoke & Carbon Monoxide Detector, AA Battery Backup, Voice Alerts, Interconnectable, LED Indicators, model 900-CUAR-V, is an alarm combo that detects smoke, fire, & carbon monoxide gas, using a single alarm. Operating through your home's wiring (120V AC power), while 2-AA batteries (included) provide battery backup during the event of a power failure, the Kidde Smoke and Carbon Monoxide Alarm is equipped with self-testing components that are always checking the unit to ensure the device is operating as expected*. Photoelectric sensing technology that senses visible fire particles (associated with smoldering fires), while an electrochemical sensor detects carbon monoxide. When a smoke, fire, or carbon monoxide event occurs, the Kidde fire alarm warns with an 85-decibel alarm sound & flashing red LEDs, and voice alerts announcing, "Fire! Fire!". For carbon monoxide detection, the alarm will sound with...2-in-1 Detection - Smoke & carbon monoxide detector combo alerts you to both smoke & fire events as well as poisonous, CO gas in a single device
85-decibel alarm alerts to smoke, fire, or carbon monoxide
24/7 Self-testing components are always checking the device to ensure it's operating as expected (not a substitute for a manual push test)
Whole-Home Alarm Activation - expands detection via hardwired connections to other Kidde smoke alarms, so when 1 alarm sounds, they all do
Easy Installation - Mounting bracket included for quick installation in 4 orientations
120V AC hardwired with 2-AA battery backup (included) - provides reliable protection, even during power failures