TFA Accuracy Thermo-Hygrometer

Before buying this hygrometer I already had two separate digital hygrometers in my home in addition to the built-in hygrometer in my humidifier. I needed one more hygrometer for a different room. I've got guitars all around my home and I need to make sure the humidity is within an acceptable range in ALL rooms. I thought this analog one looked cool.

This hygrometer needed calibration upon arrival. Out of the box it showed almost 10% higher air humidity than my digital hygrometeres (the temperature reading was correct though). Fortunately it can be calibrated by a screw on the back panel.

After calibration it remained consistent with my digital hygrometers... for a while. Then it started drifting and after a couple of months it needed re-calibration. The temperature readings remained correct and stable though.

I also discovered that even the slightest of physical bumps (for example when it toppled over on the table) will affect the calibration. Again: Only the humidity readings seem to be affected, the tempereature readings remained correct. This probably explained why the humidity readings were completely wrong after shipping from Thomann.

To sum it up:

-You can NOT trust this hygrometer upon arrival. It will need to be calibrated.

-It will also need to be calibrated regularly and ALWAYS after even the slightest of physical impact.

-It's basically useless unless you have a better quality, more stable hygrometer as a reference for calibration.

As most guitar players will probably just need ONE hygrometer I can NOT recommend this one. It can not be trusted.