Obvious ideas are often the best. For example the aquarium heater as a rod. The heating element is simply hung in the water and heats it. It is true that the principle is still the same as decades ago. But a lot has changed in the meantime. And today the adjustable Eheim heating is a state-of-the-art electronic heating device with the best available technology. A jacket made of special laboratory glass enlarges the heating surface, serves as a heat shield and ensures optimum, even heat emission. And regardless of whether you want to heat a 20 or a 1000 litre aquarium - you have 9 sizes to choose from.