Features: Multiple function, real time testing the concentration of CO2, TVOC value, temperature and humidity. Selected quality sensor, high accuracy, anti-interference, with quickly reaction speed. Equipped with large digital display with backlight, you can see the remaining electric quantity, CO2 value, TVOC value, temperature and humidity data clearly. The color circle will change(Green-orange-red), according to the CO2 and TVOC data. Application areas: agricultural planting, greenhouse vegetables, production warehouse, material processing, home interior, etc.