Product review (5 stars): Real happy with this, bought a second one, more is better (after temporarily losing one)
the only other hygrometer i ever had was a room one that sits on a shelf, it's gray and black and ok.  This was before i was forced by low humidity recently t humidify one of my guitars which is more vulnerable than the others.  i wanted one i could put in the sound hole, this has been perfect for me, good fast readings, seems sensitive  and accurate, there's some difference with the other one by a few percentage points, sometimes they're the same or only one point difference, but i like the design of the Music Nomad one the best, it can be used anywhere.  I got a second one when i thought i lost the first one, and knew that even if i found the other one, which i was sure i would, i wanted to have two.  i usually keep one in the case and one in the guitar sound hole when it's not in the case.  i like how it's easy to just pull out of the sound hole when i want to play.