the UTH is on the outside of the tank and the probe is on the outside of the pad..the thermometer is inside the tank..instead of running your mouth just to run it just to oppose my comment ,don't be a fool,READthe comment and then postNo where do I state that it's inside the tank and only a retard would put it in tank or tv vk I won do so...pictures on the box are clear enough where it goes,lol