The Aqua Buddy isMade from durable polypropylene, is easy to clean, and is sun resistant. The Aqua Buddy 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. The Aqua Buddy is ideal for dogs and cats of all sizes.