Air quality Sensor Provider: CO2 Gas Sensors, Non-dispersive Infrared (NDIR), Maintenance Free, Automatic Calibration, 400-5000ppm Range. Specification Parameters Measurement Range: 400-5000ppm Measurement Precision: ±(50ppm + 5% reading) Power-on Settling Time: 30s Data Refresh Rate: 2s Zero Setting Cycle: The sensor is automatically calibrated every 15 consecutive power-on days (optional). (Automatic calibration is not enabled by default in 15 days.) Working Condition: -10-50℃; 0-95% RH (non-condensing)