Safety Guarantee: The explosion-proof quartz glass shell is double-sealed, explosion-proof, and corrosion-resistant. Prevents your fish or turtles from being injured by touching the heater. Can be used even with low water levels: The aquarium heater can be used with a 3.5cm heater, designed for fish and turtles. EXTERNAL CONTROLLER AND BUILT-IN THERMOMETER: The external touch controller makes it easy to adjust the temperature and change the unit without getting your hands wet. The LED digital display clearly and accurately shows the real-time water temperature. Overheat Protection: It automatically shuts off if overheated, and the aquarium heater is equipped with a multifunctional intelligent constant-temperature heater, providing a safer and more comfortable environment for your fish. NOTE: The aquarium heater must be completely submerged in water. Never remove it from the water. The heating rod must be completely submerged in water to turn on.