🐠【Compact Small Heater】110-120V/60HZ oval shape design little aquarium heater, fast heating for small fish tank. 50W tank heater is for 1-6.5gallon, 100W tank heater is for 6.5-13 gallon. Heater Dimension: 2.7x1.4x 4.5 inch. The power cord is 5ft, long enough for use indoors. With 2 strong suction cups at the back side of the betta heater, it's easy to install it on to glass, acrylic or plastic tank 🐠【External Controller】easy to set the temp on the controller, only show farenheit temp, you can set the temp range from 63℉ to 94℉, temp accuracy 1℉. Every time you set the temp, just press the button over and over until it reaches to your desired temp, then stop and wait the digit flashing for 3 times, then setting is done. Keep the controller away from water, it's not waterproof 🐠【Digital Display】with led display on the midle of the heater front side, when the fish tank heater is heating, there indicator light above the digit is on red, when it stop heating, the light is off. The heater with a built-in thermometer, when temp setting is done, the led will show the water temp all the time. The led will display the set temp digit only when you press the controller