_The open chamber measurement is the only method to assess the TEWL continuously without influencing the skin surface, which is necessary for most applications. A stable measurement is achieved quickly and the next measurement can be done without wasting time. The small size of the probe head minimizes the influence of air turbulence inside the probe. The low weight of the probe ensures minimal influence on the skin structure and easy handling. Calibration can easily be checked by a small chamber at any time. This instrument is available for the C+K MPA-System, as a stand-alone device and as a wireless probe.