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

I bought these for relative humidity (RH) control in herbal medicine jars. Glued into the jars, they work fairly well, giving relative humidity readings that are consistently 2 to 4 percentage points lower than the NIST-monitored hygrometer in my lab. I can live with that since I'm tracking a range of relative humidity, not a specific value. Other reviews note discrepancies between individual units in bulk packaging, but I found they were actually quite compatible (see photo). Remember this ship is included. When my kit arrived, one unit had dead batteries while the other two died within a few weeks of receipt. I noticed that the relative humidity readings of these two devices started to drift higher just before turning off (compared to devices with good batteries), which could explain the discrepancy that others have seen. All in all, a decent price-performance ratio, despite an approx. 5% error in the relative humidity measurement accuracy.