The testo 425 is a compact hot wire anemometer with a cable-connected telescopic probe. It is ideal for simple, fast and precise determination of flow velocity, temperature and volumetric flow in ventilation ducts of air conditioning and ventilation systems as well as for localization of air leaks in the building envelope. Even in the difficult lower flow range, the testo 425 measures extremely precisely. Connection to the testo Smart App enables configuration, display, storage and documentation of the measurement directly in the app (also as a second screen). The wired telescopic probe can be extended to 820 mm, making it easier to work overhead or in large diameter ducts. All relevant calculations, such as volume flow or time and point averages, are performed automatically by the particularly robust and handy measuring device. Scope of delivery: Compact thermal hot wire anemometer with app connection and fixed telescope (max. 820 mm), incl. case for measuring instrument, calibration protocol and batteries