Feature: 1. ACCURATE 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 2. WITH ALARM: PM2.5 of indoor air quality meter warn by color. Green 0‑50, yellow 51‑100, orange 101‑150, red greater than 151. The bigger the data, the worse the air pollution. When PM2.5 is greater than 100, an audible alarm will be triggered. If both CO2 and PM2.5 exceed the standard, CO2 will give priority to the alarm 3. LONG ENDURANCE: Air quality meter built in 2000mAh rechargeable lithium battery, use the USB charging cable in the package, input DC 5V voltage, charge 3‑4 hours can be fully charged, fully charged after 7‑8 hours of sustainable work 4. COMPACT 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 5. DETECTION OBJECT: 8 in 1 air quality meter built in 5 professional detection sensors, can accurately detect the current indoor CO2, PM2.5, HCHO, PM1.0, TVOC, PM10, temperature and humidity in the air Specification: Item Type: Indoor Air Quality Meter Material: ABS Use: 8 in 1 indoor air quality meter with 5 professional sensors to accurately detect CO2, PM2.5, HCHO, PM1.0, TVOC, PM10, temperature, and humidity Battery: 1 x lithium battery(2000mAh). Package List: 1 x Indoor Air Quality Meter 1 x User Manual 1 x USB Charging Cable