This First Alert carbon monoxide alarm features a 10-year built-in lithium battery for continuous monitoring during the life of the alarm, and uses an electrochemical carbon monoxide sensor and an 85-decibel alarm to alert you to CO threats. The advanced electrochemical CO sensor detects carbon monoxide leaks from multiple sources, such as faulty fuel-burning appliances, blocked chimneys, and generators running inside or too close to homes. Because CO evenly distributes itself, it's important to have a CO detector on every level and in every bedroom of your home. This easy-to-use alarm features a digital display that shows ambient temperature as well as peak CO levels. The detector's stylish design looks great on top of a dresser or table.