The Frebis sensor is a smart and wireless sensor for determining the air quality indoors. The sensor records the CO2 content in the air in ppm, as well as temperature, relative humidity and air pressure at regular intervals and warns acoustically via a buzzer and visually via bright LEDs if the specified limit value is exceeded. In addition, the data is transmitted at regular intervals via mioty. In this way, rooms or entire buildings can be efficiently monitored. Alternatively, the sensor can also be equipped with an additional VOC sensor. The sensor is powered by 4xAA cells, which are easily replaceable. With a simple double tap on the sensor, an immediate measurement can be triggered manually. Wall mounting is recommended. Alternatively, the sensor can also be placed on desks or cabinets.