Features: 1. Aquarium Heater With Guard Protector: fast heating for different size of fish tank.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. 2. External Controller: easy to set the temp on the controller, only show farenheit temp, you can set the temp range from 18℃ to 35℃, 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 3. 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 4. Reliable Thermostat: this an automatic aquarium thermostat, after finishing the temp setting, you can be confidence on that it will maintain the tank water at the temp you set. The tank heater will stop heating when the water temp reaches to set temp, it will restart to heating when the water temp is 1℃ off the set temp. If the water temp is over 35℃, the heater will auto shut off, it will work normally again when the water temp is lower than 35℃ 5. Shut off When Out of Water: please note that this a fully submersible aquarium heater for fresh water and saltwater tank, when the top part of the heater is out of water it will auto shut off, when fully in water again it will return to normal work again Specifications: Voltage: 220-240V Wattage: 50W / 100W / 300W / 500W (Optional) Frequency: 50/60HZ Temperature Range: 18℃~35℃ Material: Plastic and Glass Application:Fresh water and Salt water Caution: 1. We may send you a plug adapter((EU, US, AU, UK,etc) according to your country . If you need another type, please leave a message after ordering or contact us directly. 2. The heating rod must be totally immerged into water and no exposure is allowed. 3. When the indicator light is on, it is working. 4. Before cleaning the aquarium or heating rod, please turn off the power for 15-20 minutes to cool off the heating rod, or you will be burned.