JR Products (HTH-A Holder Tank Heater JR Products Holding Tank Heater - Holding tank heating element is an easy and practical way to winterize your RV tanks Can be used on either fresh or septic tanks Dual voltage ready for both 12 volt and 110 volt applications Elements are thermostatically controlled and activate at approximately 34 degree Fahrenheit to stop the contents of your tank from freezing Approximately 1 Amp AC and 10 Amps DC current when in use