The Kidde KN-COEG-3 AC powered plug-in CO and explosive gas alarm protects you and your family from two deadly threats. The KN-COEG-3 includes 9V battery back up that provides protection during a power outage when AC-only units can not provide protection. By pressing the Peak Level Button you can see the peak CO level recorded by the alarm since it was last reset or unplugged. The continuous digital display shows you the level of carbon monoxide (if any) the unit is sensing as well as if gas is present. The gas sensor is a metal oxide sensor designed to detect natural gas (methane) or propane.The Kidde KN-COEG-3 provides you and your family a level of protection that you have come to expect in a Kidde product. The alarm is easily installed in any of your AC wall outlets giving you the choice of a direct-plug a 6’ power cord or a table top unit. Depending on how or where you wish to mount your unit you can get exactly what you need for a perfect application. The KN-COEG-3 is UL listed and offers a 7-year life and a 5-year limited warranty.