Review on Goabroa 12 Pack Mini Small Hygrometer Thermometer: Digital Indoor Humidity Gauge Monitor with Temperature Meter Sensor (℉) – Bulk Pack for Accurate Climate Control by Charley Martinez

These are great no frills hygrometer/thermometers for a variety of uses, but I chose them to monitor the humidity in and around my guitar cases. The fancy ones sold by musical instrument and instrument dealers use the exact same hygrometer/thermometer probes they do, but they cost many times more than those that cost per unit simply because they come in prettier packaging. I literally got 12 of them for the price of ONE of the fancier ones and I'm pretty sure they're just as accurate. I placed several of them in the same spot at once to make sure they all gave consistent readings, and they really... within 1 degree Fahrenheit in temperature and 1% humidity for all. They are also designed for panel mounting, so you can attach a small stand or clip to secure them in a convenient position in the guitar case. Place them on a decorative wall hanger that you make yourself to keep track of the humidity levels in the rooms/areas of your home etc. You just need to trace and cut a right size hole for the hygrometer body and insert it into the hole. My only small issue is that they are packaged/shipped with batteries already installed/included so you can't know how much battery life is left when you receive them, but that doesn't really matter to me. The LR44 batteries that power them are plentiful and cheap on Ebay. It's easy to keep a supply of spare batteries on hand if/when they run out.