1ACCURATE SENSING: Standalone CO2 NDIR sensor offer higher accuracy and greater interference resistant than semiconductor sensor. The concentration of carbon dioxide in the air can be accurately measured 2WITH ALARM: PM5 of indoor air quality meter warn by color. Green 050, yellow 51100, orange 101150, red greater than 15 The bigger the data, the worse the air pollution. When PM5 is greater than 100, an audible alarm will be triggered. If both CO2 and PM5 exceed the standard, CO2 will give priority to the alarm 3LONG ENDURANCE: Air quality meter built in 2000mAh rechargeable lithium battery, use the USB charging cable in the package, input DC 5V voltage, charge 34 hours can be fully charged, fully charged after 78 hours of sustainable work 4COMPACT AND PORTABLE: The compact size and portable design of the CO2 detector can be easily placed anywhere, ensuring that you can always detect CO2 levels 5DETECTION OBJECT: 8 in 1 air quality meter built in 5 professional detection sensors, can accurately detect the current indoor CO2, PM5, HCHO, PM0, TVOC, PM10, temperature and humidity in the air