Features: Intelligent carbon dioxide value tester uses air semiconductor-sensor to monitor temperature and humidity of air quality. Adopts superior electrochemical detection module, with high accuracy, stable performance, can accurately detect carbon dioxide value. Strong anti-interference ability, low consumption and long service life. The product does not need calibration, it can be tested after booting, and it can accurately detect carbon dioxide. Different colors corresponding to different air quality, green 400-450ppm, blue 451-700ppm,Purple 701-1000ppm, yellow 1001-2000ppm, red 2001-5000ppm. Hundreds of ventilation holes at the back of housing not only accelerate the convection between the air and the machine, thereby realizing effective detection, but also provide a fine heat dissipation effect. Widely applications: agricultural planting, greenhouse vegetables, production warehouse, material processing, home interior, etc. There are 4 types for you to choose, you can choose 3in1 white, 3in1 black, 5in1 white, 5in1 black according to your demands. 3in1: The large screen displays the power, CO2 value, temperature and humidity. 5in1: The large screen displays the power, CO2 value, TVOC value, HCHO value, temperature and humidity.