Review on JEDEW Mini Hygrometer Thermometer - Accurate LCD Monitor for Indoor/Outdoor Humidity & Temperature Measurement - Ideal for Humidifiers, Dehumidifiers, Greenhouse, Reptile Environments, Plants & More by Daniel Russell

Rated 4 stars because it advertised a range of 10% to 99% but none of the options were below 20%. Not really a problem considering the price and intended use. I have them in sealed containers with printer filament and silica balls. Humidity should be near zero, but all four read 20%. These are stable displays, even before I put them in the box they didn't change or wobble quickly. Not bad for the price, if you want more accuracy you have to pay significantly more. As I am expanding my thread collection I prefer to stick with this brand, at least I know they work and how well they work.