The UPETTO’s Submersible Aquarium Heater is a high-quality, durable heater that is perfect for keeping your fish tank warm. With a 300W output, it is powerful enough to heat up a 55-gallon tank in less than 10 minutes. The heater features an external temperature control system that allows you to easily adjust the temperature from 24-32 degrees. It also has a white corundum internal heat transfer medium that helps reduce heat loss. The UPETTO’s Submersible Aquarium Heater comes with a 365-day guarantee and no need to return policy.