Review on 🌡️ LayscoPro Mini Indoor Thermometer Hygrometer - Analog 2-in-1 Temperature Humidity Monitor Gauge for Home, Room, Outdoor, Offices - Display Mechanical Diameter 57mm - 1 Pack (No Battery Needed) - Gold by Orwin Greener

I waited a while before rating this product. I'm mainly interested in its ability (or lack thereof) to accurately measure moisture inside a guitar case. plus or minus deviation. I let all six cool for thirty-six hours, then calibrated them with the room humidity measured by our Nest thermostat. Luckily, the little beggars are accurate to within a few percentage points. I'm honestly amazed that this modest price would even work, and even more so at the level I've been able to rely on in one of my guitar cases.