These balls are typically made from durable, non-toxic rubber and come in a variety of bright colors to attract a dog's attention. The addition of a bell inside the ball adds an extra element of excitement, as the sound of the bell will pique the dog's curiosity and encourage them to play. Chew balls with bells are great for interactive play, such as fetch, and can also be used for solo play. The act of chewing on the ball helps to clean the dog's teeth and massage their gums, promoting good oral hygiene.