Repti Therm U.T.H. Under Tank Heaters are an ideal 24 hour primary or secondary heat source for tropical or temperate reptilian species. All of Zoo Med’s Under Tank Heaters are UL/cUL approved (GS/TuV/CE in Europe) and contain a solid state nichrome heating element. These under tank heaters permanently adhere to your terrarium, forming a solid bond for optimum heat transfer.