AT Digital USB CO2 CARBON DIOXIDE Air Temperature Humidity DataLogger Meter Monitor LCD/PC Super large LCD display and log carbon dioxide(CO2) level, temperature, humidity 12700 data logging memory;Warning carbon dioxide level Stable NDIR(Non-dispersive infrared) sensor for carbon dioxide(CO2) concentration NDIR Waveguide technology with ABC (Automatic Background Calibration) High and low threshold setting;Backlight to test easily in the dark environment