Aqua Medic Titanium Heaters are the safe alternative to glass heaters in both fresh and salt water aquaria. The unbreakable titanium housing is sea water resistant and the heaters have both overheat and dry running protection cutouts. The heaters must be used in combination with a temperature controller.Aqua Medic Titanium Heater is available in with the following wattages:+ 100 W - for aquaria 100-250 litres, length: 27 cm, diameter: 2 cm+ 200 W - for aquaria 250-500 litres, length: 28 cm, diameter: 2 cm+ 300 W - for aquaria 500-1000 litres, length: 30 cm, diameter: 2 cm+ 500 W - for aquaria 1000-1500 litres, length: 32 cm, diameter: 2 cm