Wireless Interconnected Alarms: These wireless alarms interconnect via radio frequency so that when one alarm sounds, all of them will alarm, providing earlier notification of danger Battery Operated Carbon Monoxide Alarm: Equipped with a electrochemical sensor that delivers stable performance for 10 years; replaceable battery lasts for 5 years Full Home Coverage: Up to smoke, or combination alarms can be interlinked in a network for maximum detection coverage; Customizable Wireless Network: Wireless alarms in a multi-pack have been pre-connected; simply disconnect the network and reconnect devices to create new networks based on your needs Safe Network Connection: Secured private network, preventing the alarms from creating a new network or connecting to your neighbors network Peak Concentration Memory: The LCD shows peak levels since the previous reset, notifying you of any potential leaks