MINI SIZE: This aquarium heater is super mini size, only 5cm in length, perfect for nano/betta tanks. The innovative super short size can perfectly solve the problem of traditional heater not suitable size. Temperature control range 64-93℉, suitable for 1-2 gallon fish tank. OVERHEATING PROTECTION: When the water temperature exceeds 97℉, this fish tank heater will stop heating automatically and display" H1",Fully consider of safety，You are free from “cooking fish”! Wide range of uses - This fish tank heater can be used for both fresh and marine water, it can be not only used as an aquarium heater, but also as a turtle heater, pet fountain heater. Running dry protection : Auto shut off heating and show "E1" when the aquarium heater is removed from the water, and resume functioning upon return. Built-in thermostat for accurate temperature: This thermostat keeps the heater at a constant temperature at an accuracy of 1F, much more accurate than traditional knob controlled heaters.