This is our fifth purchase of an Inkbird. Our oldest one is at least 3 years old and still working great. We use them to regulate temperatures of seedling heat mats, chick brooders, unreliable refrigerators, and oil-filled heaters. We also use one to change a refrigerator into a storage unit for tomatoes and peppers by setting the temperature at 55 degrees. Likewise, we use one on a window air conditioner in a small insulated space to have a cool room for storing other vegetables.