I've taken that sticky pad off the probe and under it is a silicon sealed wire end. So i'm assuming it works no matter which way you place it. I took the sticky pad off the one I have in my big girl Roseys cage as she tends to like to try and destroy the Acurite probe and Herpstat probe and the Acurite main unit by trying to poop on them. She doesn't get the probes as I hang them a couple inches off the floor but she has dropped a couple deuces on the unit which is really fun to clean with a paper towel soaked in F10SC....