The Eheim Heater is an ultra modern electronic thermal device for heating your aquarium. – Temperature can be precisely adjusted from 18deg to 34deg C and recalibrated if required. The control accuracy is +/- 0.5deg C. – Heat is kept at a constant level. The heating function is indicated by a control lamp. – Fully submersible. – Protected against dry running. – Laboratory quality glass jacket enlarges heating surface and ensures optimum even heat emission. – Suitable for Freshwater or Marine water. – Includes suction cup holder. – 25w heater suitable for 20-25l aquariums. – 243mm length x 36mm diameter.