I assume you are talking about hygrometer... I tried to think of why a hydrometer would be needed for cigars and I couldn't really find a reason.
Most of the stuff advertised towards cigar smokers is consumer grade.
If you want a real accurate hygrometer you have to go the scientific route.
For most cigar smokers, it just about finding some consistency. I use the HydroSet IIs in my humidors, just salt test before and enjoy.