This Kidde 10-Year combination smoke and carbon monoxide detector is easy to install and alerts your family when a fire or elevated carbon monoxide levels are detected in your home. Smoke and CO sensing technologies work together to detect real fires faster and reduce cooking-related nuisance alarms. Combination alarms should be placed outside each sleeping area and on every level of the home. This alarm is powered by a 10-Year sealed-in, non-replaceable lithium ion battery. No hardwire installation required and no need to change the batteries over the 10-year life of the alarm. Simply replace the entire unit after 10 years.