Have the equipment purchased primarily because of the hygrometer to measure the humidity in the living room. Had us in the meantime another instrument borrowed. Initially, the new hygrometer indicated about 10 percent too much. So wrapped as described for 30 minutes in a damp cloth. Then it showed around 105 percent. Using a small screwdriver on the adjustment screw corrected to 95 percent and it is already calibrated. Now both devices coincide. Are very satisfied. Can be seen very well and looks good. Good value for money!