[HD Screen with Backlight]Air quality monitor features a high-definition LCD screen with blue backlighting, data is clearly displayed and easy to read, you can know the air quality at a glance. [Accurate Measurement & Vent Design]CO2 monitor has built-in advanced digital sensor, which has fast response speed and high sensitivity. The built-in high-performance chip can quickly process the data acquired by the sensor and calculate the concentration of various gases in complex environments, outputting accurate measurement results. The innovative design with the vent allows full contact between the air and the sensor, making the measurement data more accurate and reliable. [Buzzer Alarm]When the air pollution level is too high, the air quality monitor indoor display 'POOR' and automatically sound an alarm through the built-in buzzer to prompt you. [5-IN-1 Multifunctional Air Quality Monitor]The air quality monitor adopts high- and professional sensors, which can accurately detect formaldehyde (HCHO), volatile organic compounds (TVOC), carbon dioxide (CO2), temperature (℃/℉) and humidity (%), let you fully know the air condition. The portable indoor air quality monitor can not only help us detect the air quality of our homes, kitchens, bedrooms, but also schools, offices, cars, hotels, etc. [Highlight Maximum Value & 120 Seconds Countdown]The CO2 detector equipped with a MAX button, you can check the maximum value of data detected in the current test record after power-on or calibration. After power on, the CO2 meter screen count down 120 seconds before entering the test mode. During the countdown, indoor air quality meters can be placed in a ventilated place to make the more accurate.