The pet fountain is made from durable plastic, is easy to clean, and is sun resistant. The pet fountain uses an internal float and valve system. When your pet drinks and the water level drops, the valve opens and replenishes the water supply. As the bowl refills, the float rises and closes the valve. This simple but effective system will not overflow, and no training is required for your pet to use it. Pet Waterer is ideal for dogs and cats of all sizes.