I improved my hatching success with these two pieces of equipment. The Little Giant Still-Air Incubator is notorious for hot and cold spots. With this type of thermometer I am able to monitor temps anywhere in my incubator, it cost me $5.00 bucks online(ebay). My wife brought me a couple of the small computer fans from here work. Once I added one of the fans the hot and cold spots disappeared. Before the fan, the temps could swing drastically from the top of the incubator to the bottom. I have seen differences of nearly 5 degrees within about 3 inches.