The First Alert BRK SC7010BV Hardwired Talking Photoelectric Smoke and Carbon Monoxide Alarm features a photoelectric smoke sensor and an electrochemical carbon monoxide sensor. The exclusive voice alarm not only alerts you whether the threat is smoke or carbon monoxide but also tells you the location of the danger; you can pre-program up to 11 locations in your home. The 120-volt CO smoke detector is designed to be hardwired into your home or office and offers a battery backup for continued functionality in the event of a power outage. The one-touch silence/test button makes it easy to operate. Connect them to other compatible hardwired detectors as part of a system for larger spaces.