Review on 🌡️ TESSAN WiFi Smart Temperature Controller: Plug-in Digital Thermostat for Heating and Cooling, Compatible with Alexa and Google Home, App Monitoring, Recording, Alarm for Homebrew, Seed Germination, Reptile Keeping, Greenhouse, and Aquarium by Theresa White

I bought two of these at different times. One works as expected, does nothing between high and low temperatures, the other heats or cools to the opposite temperature, defeating every purpose I can think of. For my greenhouse application I want it to do nothing if the current temperature is between the set high and low temperatures. I've seen the explanation that the heating/cooling on the other end was an upgrade, but it's costing me money and I need to replace it with a different type of switching mechanism. set different high/low temperatures for different times of the day so I can take advantage of changing conditions and seasons. As other reviewers point out, a thermostat is never accurate. I have a mercury thermostat in my greenhouse and they never match. This product is always higher or lower than the mercury thermostat listing. I gave these three stars because one works perfectly as advertised and the other doesn't.