Real-time CO2 monitoring: The CO2 detector is equipped with a high precision NDIR sensor to accurately monitor the concentration of carbon dioxide. It is convenient to easily know the comfort and health of your life through the CO2 value, room temperature and humidity display. Sound alarm with silent mode: When the CO2 level exceeds 1000 ppm, the audible alarm will sound to warn you of air pollution. The audible alarm can be temporarily disabled by pressing the power button. If you don't need the alarm sound, you can turn off the beep function directly by entering the setting mode. Three-color display alarm: The digital LCD screen displays three colors based on the CO2 detection ranges: Green : 400~1000PPM, yellow: 1000-3000 PPM, Red: 3000-5000PPM. It is very easy to distinguish the concentration level of carbon dioxide in the air. Easy to use: Open and long press the power button and after 10 seconds countdown you are ready to use it. The air gas detector has an automatic calibration function and can be calibrated manually in a well-ventilated place. Compact size and portable desktop: Compact size 80*80*50mm, it is convenient for portable and desktop use. It is suitable for indoors and outdoors to detect carbon dioxide (CO2) at home, office, school, hospital, car and various places where it is important to monitor air quality.