Product review (5 stars): Simple and works extremely well.
Easy to use. Doesn't drip. My favorite humidifier so far.

The humidistat works great too. I have two. T hey both agree on readings and also agree with another brand humidistat I have. (All typically within 2%)

Only issues is that it can't really be used in the sound hole in my Martin guitar and case. The problem isn't really in the unit, it is in the case humidifier/humidistat combo. The Martin case is a *very* snug fit with the guitar; it actually touches the strings all the way down to almost the bridge. while the humidifier and humidistat stick up above the strings just a bit. Enough that putting this humidifier between the strings results in the strings getting pressed into the guitar too much when I close the lid.  I put the humidistat in the space where the cutout is (inside a small sock to avoid scratches) and the humidifier by the headstock. It works well enough

For my other guitars in bags, this unit works great.

I won't ding this design any stars for Martins case design though.

I would definitely buy them again.