Features: Color screen display: The color screen display makes it easier for you to read and identify in darkness. Wide application: The portable size enables you to take it anywhere you go. It can be used at home, office, shopping mall, hotels and etc. 3 in 1: It can detect real-time CO2 concentration, humidity, and temperature. CO2 detection range: 400-5000PPM.Temperature detection range: 0-50℃. Humidity detection range: 0-99%RH. CO2 detector: The color ring will change according to the current CO2 concentration. USB charging: It can be charged through the charging port of any mobile device. The battery icon flashes in the charging state and it stops when it\'s full. Any problems, feel free to contact us. Honor to serve you!