High-definition LED display: LED digital display, real-time monitoring of the temperature inside the fish tank. EXTERNAL TEMPERATURE CONTROLLER: The controller adjusts the temperature without getting your hands wet. It's easy to control the temp from 68℉/20°C to 94℉/34°C; Check the size chart to find your desired fish tank heater. Over-Heat Protection: After set the temp you want, automatic switch device and temperature detection system, water heater will turn off automatically when its temp reaches your pre-set, also will turn on when lower than your set, relieved and simple operation. High Quality: High temperature resistant ABS shield, protect fish and other livestocks from punching and scalding. High quality ceramic PTC board, fast heating and heat dissipation. PID Frequency conversion energy saving and safety. Function: By using the temperature controller, precise thermal control can be performed by a simple thermostat for precise adjustment. It is easy to install and use, suitable for freshwater and marine aquariums, aquaculture, glass containers and hydroponic systems!