First Alert Plug-in Electrochemical Explosive Gas and Carbon Monoxide DetectorThis 3 in 1 gas alarm warns against natural methane, propane and carbon monoxide. The digital display makes for easy reading during an alarm or when, any button is pressed. The alarm plugs into any standard outlet with no additional mounting necessary and comes with a line cord, which offers multiple placement options. The alarm also comes with a battery backup in the case of a power outage and utilizes an electrochemical carbon monoxide sensor for