This willow ball is great for cats and birds as well as rabbits. The willow is tightly woven, ensuring that this ball will last a long time. The natural peeled willow has a nice cream color. Great for chewing, rolling and/or tossing in the air. The balls range from 2.75 to 3.0 inches (6.985 to 7.62 cm) in diameter and are hollow inside.