Review on Digital Indoor Thermometer Hygrometer: Room Humidity Gauge with MAX/MIN Display, Big Screen, Stand, Wall Hanging, and Magnet (3-Pack) by Mike Malvo

Very simple devices. After inserting the supplied battery, the device switches on. I was a bit concerned at first because all 3 I got showed 80+ degrees. Realizing that they had been sitting on the porch in a fairly warm spot for several hours, I left them alone for a while. I came back and they were all cold enough to show the actual temperature. I installed one upstairs in the office, one in the kitchen by the fridge and one next to our thermostat. I already knew that every place I put the device would/should show different temperatures. Miraculously, these devices have confirmed that our home cannot maintain a constant temperature in all zones/rooms. To assess the accuracy of each, each took turns standing next to the thermostat for at least a day. I checked the readings several times a day, and most of the time it showed the same temperature as the thermostat (it was off 1 degree every other time). I think $18 for a pack of 3 of these devices is a great deal. Easy recommendation.