Review on Gold Guitar Violin Thermometer Hygrometer: Accurate Temperature and Humidity Meter for Instrument Care by Jasmin Rojas

I need a small inexpensive hygrometer that doesn't require batteries. These meet my requirements. Remember that bimetal thermometers and metal coil hygrometers are never that accurate. I bought them as an "indicator" not a gauge. The problem is that 2 out of 6 dials are stuck. The hygrometer scale does not change when the relative humidity changes from less than 30% to more than 60%. I removed the back cover and tried to detach the dial by rocking it back and forth a few times. For one, it helped a little, but it's still sticky and doesn't move until the humidity changes by more than 30% or so, and then moves just a little. The other just stands still. Oddly enough, all thermometers work properly. If you're willing to buy a few and try them out, you might find ones that work. I will keep 4 and return 2. I bought 6 and out of those 4 it works as expected. Pros: - They are small, 1.7 inches (43mm) in diameter and just under 0.4 inches (10mm) thick. - They look pretty good - The ones that work have an accuracy of +/- 5F and maybe +/- 10% RH. Humidity - Some of these seem to be fairly accurate to within a few degrees and better than 5% so you might be in luck. Cons: - 2 out of 6 had stuck dials for my purposes though)