The measuring instrument can also be used to measure flow and return temperatures. When working at temperature measuring points that are far apart, the testo 115i makes the application considerably easier - thanks to the wireless connection to the smartphone or tablet, and when using the testo 549i high-pressure measuring instrument at the same time, individual parameters of refrigeration systems, such as superheating and subcooling, can also be calculated. The testo Smart Probes app installed on the end device allows users to conveniently read off their measurement values. All measurement data is displayed either as a graph or in tabular form. Finally, the measurement data logs can be sent directly as PDF or Excel files.