In spaces where many people stay over a certain period of time such as kindergartens, elementary and secondary school classrooms, hospitals, postpartum care centers, multi-use facilities, the air quality quickly deteriorates. An indoor air quality monitor consisting of various sensors can be installed to always maintain a comfortable environment. Using the monitor, you can check the air quality in real-time and open the door or start the ventilator at will to keep a proper environment. The MB-350 series, which can both individually and collectively measure the CO2, CO, VOCs, temperature and humidity, is being installed in many countries as well as in Korean classrooms to check the air quality in real time.