Measuring the carbon dioxide content of indoor air is critical to indoor air quality. To get fast and accurate results, you need a suitable measuring device. The compact CO2 measuring device - testo 535 with a practical mobile app allows you to carry out this important measurement easily and efficiently - and thus ensure comfort and a healthy indoor climate. Thanks to the robust infrared sensor technology, the measured values are reproducible and comparable even over longer periods of time. Ideal for repeated comparative measurements. The device also performs time and point averaging. Thanks to the testo Smart App, the measured values are stored and visualized as a table or graph. The application not only assists in configuring the device, but also turns your smartphone into a second display!