Product review (5 stars): smaller than a pack of gum
Another one here who bought this specifically as a humidity meter for their guitar case.  24 hr exposure to the salt test yielded a RH of 73%, giving this hygrometer an accuracy tolerance of +/- 2%.

It's built surprisingly sturdy for something this inexpensive ($18.50 total).  I was expecting the usual sloppy chinese plastic garbage, but the buttons and everything else are tight and the whole thing is smaller than a pack of gum.  Battery included.

The hygrometer on this isn't able to be user calibrated, but it's very accurate out of the box, nonetheless.

I was going to buy the&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Oasis-OH-2-Digital-Hygrometer-w-clip/dp/B0018A21QC/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Oasis OH-2 Digital Hygrometer w/clip</a>, but this is practically same model, just with a different brand name printed on it...and a much lower price.  However, the Oasis comes with a metal clamp, magnet and 5 year warranty (as opposed to 1 year on the Inkbird), so their price isn't horribly inflated.