First Alert® direct plug carbon monoxide alarm is easy to install. Just plug it in. Installation couldn't be easier. Once installed, it uses 40% less electricity than other brands of plug-in alarms. The First Alert FCD2N is a basic plug-in carbon monoxide (CO) detector with an 85-decibel alarm. The FCD2N has a test/reset button for testing and temporarily silencing the alarm, a red alarm indicator light, a yellow service indicator light, a green power indicator light, and a 5-year limited warranty. This alarm lacks a battery backup--which in most cases is not necessary because heat sources, such as most furnaces, dryers, water heaters, and electric space heaters, will all shut off when power is lost. A wood burning fire, furnace, or other combustion heaters are exceptions because they can still generate CO with power off. Therefore, the FCD2BT would be a better choice for a house heated with wood, coal, or similar fuels. This alarm is recommended for use in hallways and living areas. A manual is included with the unit. Features: