The Juwel Aquarium Automatic Heater has been designed for use inside any aquarium as a main component of the Juwel filter system. If you do not have a Juwel filter system the heater comes supplied with suction cups to fasten the Automatic Heater to the glass pane of your aquarium. If you do have a Juwel filter system you will position the heater inside the Filter Box ensuring that the heater is always positioned in the water flow and thus enabling an even distribution of warm filtered water. A heater holder is supplied to fit the heater into the filter system.