Aquarium Heater Indicator Light The power indicator lights up which means the heater is starting to work. When the water temperature reaches the set temperature, the power indicator turns off automatically High quality electrical resistance wire, uniform heating, long service life. . High strength heating cable, double waterproof protection, long heating life. Double layer waterproof, can control the water temperature, easy to adjust and read the temperature. Equipped with two strong suction cups, strengthen the heating rod to prevent it from falling.