Durability is created with multiple layers of flexible materials. Compared to other toys, Mighty Dog Toys have no hard edges. The result is that this toy does not promote chewing - great when you're trying to discourage chewing habits. The core of this toy is tough, durable squeaky balls, so if your dog does get to the core it's like having new toys to play with! These balls may seem plush on the outside, but all the durability features are internal making this Micro Ball toy soft, yet MIGHTY strong.