Extech EA80 Easy View Indoor Air Quality Meter/Datalogger Measures CO2, temperature, humidity, dew point, and wet bulb Checks for Carbon Dioxide (CO2) concentrations Maintenance free dual wavelength NDIR (non-dispersive infrared) CO2 sensor CO2 measurement range: 0 to 6,000ppm Temperature measurement range:-4 to 140-Degrees F (-20 to 60-Degrees C)