The CO2 / carbon dioxide measuring device has a measurement range of 0 to 9999 ppm. In addition to measuring carbon dioxide, the device also features a carbon monoxide (CO) sensor with a measurement range of 0 to 1000 ppm, as well as a temperature and humidity sensor. This allows the device to cover a wide range of measurement tasks. It is used, for example, in occupational safety to check the climatic conditions in office workplaces. During measurement, the values are stored, with the capacity to save up to 5000 measurement points. For each storage point, the CO2 and CO levels, as well as the temperature and humidity, are recorded. After a measurement run, the stored values can be viewed directly. For further processing, the recorded measurements can be transferred to a computer via the Micro-USB interface. When connecting the device to a computer, it is recognized as a mass storage device. The stored measurement values are saved in CSV file format, allowing for direct further processing. The built-in 1500 mAh battery enables mobile use. To charge the battery, the device can be connected to a 5 VDC power supply via the Micro-USB interface. During the charging process, the device can still be used to perform measurements.