The Extech CO210 is a Desktop Indoor Air Quality CO2 Monitor/Datalogger. Measurement ranges are 0 to 9,999 ppm (CO2), 14 to 140°F (-10 to 60°C) for Air Temperature and 0.1 to 99.9% for Relative Humidity. It features Minimum/Maximum CO2 value recall, Year/Month/Date/Time display, and an Automatic Baseline Calibration (minimum CO2 level over 7.5 days) or manual calibration in fresh air.