Unfortunately for me unusable

Have equal 2 hygrometer and ordered both regenerates and following the instructions. Both wrapped in a damp Lapen and waited half an hour then put back to 100% with the set screw. After some time (after a day) shows that a 21% to me and the other 33% interest. Both show the temperature properly but that it is now broken ??? Therefore I have endschlossen to return both units.

Design and appearance look good but to me not useful because the deviation from the hygrometer is too large.