http://www.eheim.com/base/eheim/inhalte/indexd50d.html?key=liniendetail_24552_ehen
•The temperature can be precisely adjusted from 18° to 34°C and readjusted if required. The control accuracy is +/- 0.5°C.
•The heat is controlled to a constant temperature. The heating function is indicated by an on/off control lamp
•The heater can be fully immersed, is protected against running dry and is suitable for fresh or marine water.
•The glass jacket enlarges the geating surface and ensures optimum even heat transfer. Thus, a smaller wattage than other brands will heat the same volume of water.
•Jacket of laboratory safety glass
Hope this helps.