About this item 【Advanced Air Detector】This multifunctional air quality monitor can accurately detect the current CO2 concentration, temperature and humidity in the air. It can help you understand the indoor air quality and provide a safe environment for your home. 【CO2 concentration stages】This CO2 detector is designed with 3 stages of CO2 concentration - normal stage (400-999ppm), warning stage (1000-1999ppm), and danger stage (2000-5000ppm). Please note: The CO2 level in the air is not a fixed data, it changes in a range at any time, so the reading on the display is fluctuating. 【Convenient Calibration】The CO2 detector is plug and play with a built-in accurate air quality infrared (NDIR) sensor, and it only takes 30 seconds of initialization after touching the switch to get stable and accurate data. Also, you can connect any 5V adapter to support charging while working. 【Long Battery Standby Time】The indoor CO2 monitor is embedded with 2500 mAh lithium battery, which supports long time continuous use, this CO2 tester uses a large 2.4-inch color screen, which is designed to increase the brightness of the displayed data, so that even the elderly can see clearly. 【Wide Application】This portable CO2 tester is compact and easy to carry, and can be used in grow rooms, offices, kitchens, schools, kitchens, bedrooms, cellars and cars. If you have any quality problems, please contact us in time, we will provide you with satisfactory service.