For use on hardsided waterbeds only Specifically designed for our European customers, this 220v heater is the best on the market today. Thermal Guard checks every unit before it's shipped. We subject each one to more than twelve times the normal voltage in our 1500-volt insulation breakdown test. And we make sure it's calibrated to give you precisely the temperature you dial. The series 100 comes with an unbreakable control knob, a tamper proof housing, a durable heater pad that's fully grounded and insulated.