I just got one of the Zoo-Med UTHs for my ball python two days ago. I have a 10-20 gallon on a 10 gallon tank. This thing sat at 89 degrees for two days and i go in there today and in about 2 hours time it had heated up to 98! This thing is not that great. my poor snake. I'm not really willing to pay 40 dollars to control a heater that only costs 25. I'm going to try a couple different things first, but they won't help with temp. spikes like that. I will never buy one of these again.