This is a really nice, easy to use aquarium heater. It is incredibly durable & fully submersible - that means you can even put it in your fish tank horizontally, because the power cord can be under water, which makes the heater easier to hide/less noticeable. It also has a light on it to let you know when the water is being heated & when the water is at the desired temperature - which is essential to keep your fish and/or corals alive! Make sure you know the correct wattage/power you need for the aquarium size you own & the optimal temperature for the types of fish or corals you have! I own 2 aquariums - a 30 gallon saltwater reef tank & a 55 gallon saltwater reef/fish tank.