Three in one: The carbon dioxide detector can monitor the carbon dioxide concentration (400-5000PMM), temperature (0-50C), humidity (0%-99%RH) around you in real time, refresh every 2 seconds, the data is more accurate, Built-in high-performance chip, faster detection! LCD Display + Smart Backlight: Large LCD screen and Smart Backlight help you read more easily, CO2 concentration, Hcho and Tvoc at a glance, even at great distances! And its small size makes it convenient for you to carry around. USB rechargeable battery: built-in 2200mAh high-capacity battery, can work for 12 hours, only supports 5V adapter or computer USB charging. More functions: intelligent early warning system, gas identification algorithm, multiple interference prevention, air convection technology, greenhouse compensation calibration, suitable for agricultural planting, production warehouse, raw material processing, home, school, office and other occasions. Note: Due to the unstable atmospheric environment, the sensor of this product is sensitive to the environment, and the data may fluctuate slightly! The working principle of infrared is to determine the CO2 concentration by emitting infrared light waves from the infrared lamp in the module and the receiving time of the receiver at the other end. The accuracy is very high. The working principle of infrared is used in industrial CO2 gas measurement equipment. In addition, the working principle of semiconductors is to determine the concentration of CO2 by sensing the content of irritating gases in the air. The advantages of semiconductors are that the test response is fast and the overall cost is low. big.