The thermostat will regulate the temp of your UTH. It's a necessity if utilizing this method of heat for your snake. The UTH's can get VERY warm and if left unregulated could result in your snake being seriously injured and burned should they decide to lay on the section of the tank it is mounted to. Also, when using the UTH, put it under one side of the tank, NOT in the middle. This will assist in establishing a "hot" and "cold" side for your pet.