I put my prob for the thermostat In the egg box right on top of the eggs. Thats if I only have one clutch. The thermometer goes in the same place in each egg box. If I have more than one clutch I hang the probe from the Helix Down from the top of the incubator. I place in in the center of the incubator. Then I have two pc fans running to keep an even temp from top to bottom. Most of the time when I run it with the probe hanging the top Is at about 90 and the bottom is about 88.5 to 89. It has worked great for me. I do have a thermometer probe in each egg box. So I can keep track of each box.