REPTITHERM UNDER TANK HEATERIdeal 24 hour primary or secondary heat source for tropical or temperate reptilian species Ul cul approved and contains a solid state nichrome heating element Permanently adhere to your terrarium, forming a solid bond for optimum heat transfer 4X5 IN 4 WATT ideal for 1 to 5 gallon tanks 6X8 IN 8 WATT ideal for 10 to 20 gallon tanks 8X12 IN 16 WATT ideal for 30 to 40 gallon tanks 8X18 IN 24 WATT ideal for 50 to 60 gallon tanks