ReptiTherm® 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. Inexpensive, low wattage heaters. 24 Watt Excellent secondary heat source.