Cautions: 1. Please confirm that the power supply voltage matches the rated voltage before use. 2. For all the glass heaters, please carefully examine whether there is any damaged part before installation. Do not use it if it has a damaged cord or crack and contact with us. 3. IPX8 design, non-detachable, do not disassemble it, otherwise it will damage the heater. 4. The heater MUST be fully submersed under water before plugged in. 5. Unplug it and wait for at least 10 minutes before changing water or taking the heater out of water; it is forbidden to take it out immediately after unplugged. 6. Do not bury the heater under sand. Tips for Using Aquarium Heaters: 1. To get an even and thorough heat distribution in the tank, it is recommended to place the heater to an area with good water circulation. 2. The aquarium temp will fluctuate depending of the room's ambient temp so it is normal that it has differences within ± 3°F, and if the room temp is below 60°F, you need to choose a more powerful heater than recommended in the list. 3. To avoid injury, do not touch the heating part directly.