Review on 12-Pack Small Digital Temperature Humidity Meters Gauge Indoor Thermometer Hygrometer LCD Display Fahrenheit (℉) for Humidors, Greenhouse, Garden, Cellar by Charles Galan

Mine wasn't as accurate as other reviewers have said, plus one arrived with a cracked display. I used a jar with packets at 62% relative humidity. Leave them in a closed jar for 2 days. I also put a more expensive reader in a jar for them. My more expensive sensor showed 62%, as did one of them. 3 of them read 60. The rest were @59 with one at 58. Close enough I think.