Duct CO2 Sensor, +/-2% RH Transmitter, 10K-3[11K] Thermistor, 0 to 2000/5000 ppm (programmable), 60 Sec Response Time, NDIR Sensor, 4-20 mA or 0 to 10 VDC, Self Calibrating, 5 Year Calibration Interval Recommended, LCD Display