10-Year Worry Free Hardwire Smoke Detector with Battery BackupThis Kidde 10 Year Worry Free smoke detector is easy to install and alerts your family when fire or smoke is detected in your home. Smoke 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 need to change the batteries over the 10 year life of the alarm. Simply replace the entire unit after 10 years. Smoke detectors should be installed