Easily attached to inside of aquarium glass with sucker Easy to install, just drop it in the tank and attached the suction cup to the inside of the tank for easy and accurate . Clear and easy to read scale that tells you, unmistakably what the temperature is in BOTH Celsius and Fahrenheit degrees. Being that this thermometer is inside the tank, it gives a much accurate of the water temperature than those placed on the outside. It floats and is secured by a included suction cup.