Review on ETHMEAS Reptile Terrarium Digital Thermometer and Hygrometer - Indoor Outdoor Temperature Gauge and Humidity Monitor for Pet Keeping by Michael Bryan

They are more accurate than I expected given the price. I installed 17 of these side by side and took temperature and humidity readings over the course of a week. They are very accurate and they are very accurate to each other. Typically, the Fahrenheit temperature between 17 of them was within 0.6° of each other. They also seemed pretty accurate considering other thermometers I've used in the past. They have a clip for attachment and a magnet. The magnet is quite strong but could be stronger. Moisture readings typically vary within 1% of each other. It also seems very accurate to me. I am very happy with these units.