This is the dental toy dogs are GUARANTEED to chew! The durable nylon bristles and rubber nubs of the Bristle Bone by PetSafe provides a unique chewing experience. The irresistible, replaceable Gnawhide® treat rings ensure long-lasting enjoyment and are easy to replace. The design of the Bristle Bone makes it impossible for dogs to gorge on treats. You can even squeeze some doggy toothpaste on the bristles so that your dog can "brush" his teeth as he chews! Toy unscrews to load treats and clean. Comes packed with another set of four natural rawhide treat rings. Additional Gnawhide treat rings sold separately.