High Accuracy-- High accuracy NDIR infrared CO2 sensor built into the rear air vents. 400-5000 PPM detection range. 1 PPM measurement accuracy. The subtle changes in the quality of the air can be detected and recorded accurately by the CO2 meter. Easy to Use-- Built-in 3-color indicator lights. The colors red, yellow, and green represent bad, normal, and good air quality conditions. The CO2 detector automatically beeps when the CO2 concentration exceeds the predefined threshold of 1000 PPM. One Button Operation-- Super easy to operate with just one button. Double-click to enable/disable the beep function. One click can change 6 different screen brightness. The innovative auto-calibration function has been specially developed for the most accurate results. Portable but Powerful-- Exquisite size of 70*80*35mm. Light as 150g and easy to carry. USB fast charging ensures that the CO2 detector lasts a long time. You can even use the special LCD screen as a makeup mirror while turning it off. 3 in 1 CO2 Detector-- This 3 in 1 air quality monitor helps you get real-time temperature, relative humidity and CO2 concentration. Allow you to have a cool and comfortable living and working environment.