This small aquarium heater is only 5cm in length, takes up less space, and is easy to hide in the fish tank. The temperature range of the American Fahrenheit model is 64~93°F, and the temperature range of the English Celsius model is 18~34°C. It is powered by a 5V/2A USB power supply, which is very safe. The heater maintains a constant temperature through a built-in chip and has a precise temperature display. It also features overheating protection and power-off memory function, making it suitable for small fish tanks of 1~5L, fresh and sea water, turtles, pet fountains, and plant seedlings.