I recommend the probe be placed between the cages directly on the heater. Then you need to determine what temperature do you run the heater to maintain the desired temperature inside the cage. A good place to start is 3 or 4 degrees higher than the temp you want inside the cage. Your heater will always run a little warmer than the inside of the cage. This will NOT harm your probe. This will allow you to maintain the most consistent temps possible. :-]

I'm glad you like the cages! Thank you!

Jeff Ronne Sr
Boaphile Plastics