I use the ultratherms. I have gotten mine from Reptile Basics. You absolutely DO need to use a thermostat. These pads can easily approach 110 in no time. Having said that, I love these pads and will only get these if I need a UTH. Forget ZooMed. Some of the reasons I like the ultratherms: you can use foil tape to attach them to the bottom of your enclosures (no self-sticking), they do not get as hot as ZooMed so no worries about overheating, you can "sandwich" them beween your tub and stand/rack with no problems (do that with a ZooMed and you're asking for trouble - yes speaking from experience). These are nice pads for affordable prices, but please DO use that t-stat!!!