Features: 1. This aquarium heaters have indicator lights to let you know when the heater is on. It will be red when heating and green when the proper temperature has been reached. 2. The heating rod uses a built in electronic theromstat to automatically maintain water at 78° F (26℃)which is ideal for most tropical fish. No adjustment is requried. 3. Ideal for aquariums between 1.3 to 2.6 gallons（5-10L） with hoods or glass canopies 4. The heater is fully submersbile and can be installed vertically or horizontally. It's small footprint makes it easy to conceal behind plants or other decor. 5. Please read all label information upon delivery. DO NOT plug heater into an electrical outlet until it is placed inside the aquarium. Specifications: Voltage: 220-240V/110-120V Wattage: 20W FixedTemperature : 26℃（78° F） Material: Plastic 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.