Product description Item Package Quantity:1 First Alert BRK Brands Hardwired Combo Smoke & Carbon Monoxide Alarm: The First Alert SC9120LBL hardwired combination smoke/CO alarm connects directly to your home electrical system. In the event of a power outage, the smoke/CO alarm is equipped with a 10 year lithium battery-backup. The battery drawer is shipped pre-locked so battery will not be discarded prematurely. The 'Smart Technology' system is designed to reduce nuisance alarms. 'Latching alarm indication' remembers which unit initiated an alarm. The 'perfect mount' system features a gasketless base and a mounting bracket that keeps the alarm secure over a wide rotation range to allow for true alignment. Under normal conditions you should not have to replace the battery for the life of the alarm. The First Alert BRK Brands Hardwired Combo Smoke & Carbon Monoxide Alarm with 10-Year Sealed Battery is a performance rich solution that includes numerous safety enhancers to ensure the maximum in overall protection. Capable of sensing both smoke and carbon monoxide, this alarm features an Electrochemical Carbon Monoxide Sensor that allows for the most accurate detection of carbon monoxide when compared to other sensing technologies. First Alert BRK Brands Hardwired Combo Smoke & Carbon Monoxide Alarms feature a near effortless installation process and are easily maintained. The premier in functionality and affordability, this smoke and carbon monoxide alarm utilizes Intelligent Sensing Technology to drastically reduce the amount of nuisance alarms triggered. A single button test/silence function and Dust Cover have been included to increase overall convenience and additional peace of mind. A Perfect Mount has also been implemented. This addition effectively increases the number of installation options tenfold.