The testo 635 offers the possibility of testing and analyzing air humidity, material moisture, U-value and the dewpoint in compressed air systems. In addition to measurement with classical probes, a wireless measurement over up to 20 m distance is also possible with the testo 635. This eliminates damage to the cable or difficulties in handling.The wireless probes are available for the measurement parameters temperature and humidity, up to three wireless probes can be recorded and displayed by the testo 635. The optional plug-in radio module can be retrofitted at any time. The testo 635 stands out thanks to its intuitive operation and clear menu structure. For example, for measurementsrat different measurement sites, the testo 635-2 provides the advantage that the measurement values can be allocated to the respective measurement site. For long-termrmeasurements and material moisture measurements, the instrument can be switched between different user profiles. The testo 635 is available in two versions. The version testo 635-2 has extended instument functions such as an instrument store, PC software, direct display of material humidity and the possibility of connecting a U-value probe.