Review on 🌡️ JEDEW 2-Pack Mini Hygrometer Thermometer: Ultimate Digital LCD Monitor for Indoor/Outdoor Humidity Meter, Temperature Control in Humidifiers, Dehumidifiers, Greenhouses, Reptile Habitats, Plants, and Humidors - Fahrenheit(℉) or Celsius(℃) by Marc Burke

I used them in a terrarium to see what happens with temperature and humidity. Now I know and I don't care if they fail now. I first tried using salt in a cup of water in an airtight bag - I think this method provides 70% moisture if I remember correctly. Nevertheless, they pointed out what to do with this technique. I've had other brands that fail after a few weeks and with this brand I've had two and now I have one that works after about 6 or 7 months. The other showed a temperature that matched the other, but the humidity was either too low or too high. It did what I wanted, which was to get an idea of the humidity and temperature inside the terrarium, and I wasn't expecting or caring if they would last long. By the way, I bought another popular brand in a pet store much more expensively and failed earlier. They seem to have the same basic design. If you really want a reliable block that will last, I think you need to either buy lots of these (for comparison) or buy a lab/commercial replacement block. I gave this 5 stars on top of the overall rating because one of the two failed after only a few months. If you don't need them for long, this will probably work.