*Brand new in original packaging Hydor ETH External Thermal Heater In-Line Aquarium Heater suitable for all canister filters with 5/8" flexible hosing. No danger of damage if unit is run dry for short period as the ETH will switch itself off before overheating. Hydor ETH - External Thermal Heater fits in line with your filter tubing Reliable, Simple to Use, Extremely Accurate Suitable for Freshwater and Saltwater aquariums Ideal for tropical fish breeding situations. Temperature control is adjustable between 66-90 deg F. Includes 2 Year Warranty from date of purchase. Heats with high efficiency and designed to avoid temperature variations caused by poor water circulation. The ETH external In-Line heater uses the advanced PTC system, which is a special polymer sheet, silk-screened with heating ink (like your cars windshield defroster) instead of metal coils. This state-of-the-art system allows the unit to be left running without water for a short time with no damage. For indoor, in-line use only, the ETH external heater has an adjustable heating control, and a hanging hook for easy placement outside your aquarium. Requires tubing. Specifications: 300 Watt 5/8" ID 53-80 Gallon Tanks