Obvious ideas often are the best ones. For example, the aquarium heater as a rod. The heating rod 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 EHEIM adjustable heater is an ultra-modern electronic thermal device with the best available technology. A jacket made from special laboratory glass increases the heating surface, serves as a heat shield and ensures optimum even heat emission.