The auomii Mini Submersible Aquarium Heater is a small, durable heater that is perfect for keeping your mini fish tank warm. With a rated voltage of 100-130V and a small size of 5-20 gallons, this heater is perfect for use in both saltwater and freshwater environments. The smart features include a built-in thermometer, dual temperature sensors, and an LED display. The heater also has a safety feature that prevents electric shocks, and a reliable design that ensures long-lasting use.