Extech CO100 Indoor Air Quality CO2 Monitor is used to measure Carbon Dioxide (CO2), air temperature and humidity with user programmable visual and audible alarm. Never have to worry about maintenance on the NDIR (non-dispersive infrared) CO2 sensor. Air quality is easily read and understood in the display of ppm Good (0 to 800ppm), Normal (800 to 1200) and Poor (>1200). The Extech CO100 Indoor Air Quality CO2 Monitor comes complete with a universal AC adapter.