The hygger 200 300W 500W Aquarium Heater is a high-quality, durable heater that is perfect for keeping your fish tank warm. With a build-in external IC temp controller, it is easy to set the temperature to the perfect level. The heat indicator lights on red when the heater is started, and they will turn yellow once the temperature has been reached. The temp accuracy is +/- 1F, so you can be sure that the temperature in your fish tank is always accurate.