Hydor ETH In-Line (UL) Aquarium HeaterThe Hydor ETH In-Line (UL) Aquarium Heater is super safe with its self-limiting PTC heating element that guarantees maximum safety against any risk of overheating. This heater is built with solid self-extinguishing materials for extra safety. Offers high precision electronic temperature control with signal light. Easy to connect to any canister filter, this universal heater is suitable for marine and tropical aquariums. The exclusive technology and the high quality components guarantee a long lasting product.