The Kidde KN-COU-B is a carbon monoxide monitor that indicates to the presence of low CO levels. Like smoke and CO alarms, this CO monitor samples the air in your home and sounds a loud alarm to warn you of life threatening conditions. In addition, this monitor will indicate low levels of CO (below 30 PPM) which may have health implications if you suffer from certain pre-existing health or medical conditions. The digital display feature adds an advanced level of monitoring showing CO levels as low as 10 PPM. This monitor includes a slide-out battery door that gives immediate access to the batteries and a safety feature that makes it difficult to close the door without the batteries being installed. Easy installation options include wall mount or table top placement. A quick reference guide of possible alarm conditions is included, and inside cover of battery door explains what to do in case of an alarm.