With the Eheim thermocontrol-e heating rod, your fish will experience the perfect temperature with even greater accuracy in any aquarium. The principle is still the same as it was decades ago, but now the Eheim controller heater is a state-of-the-art thermal device. The temperature can be precisely set and is measured and maintained even more accurately through electronics. The special laboratory glass casing increases the heating surface, acts as a heat shield, and ensures even heat distribution. Whether you want to heat a 20 or 1200-liter aquarium, you can choose from 10 sizes. Precise temperature setting from 20 to 32 °C.