The ultra-bouncy, natural rubber Kong Jump 'N Jack is Kong's latest additon to long-lasting interactive dog toys. Each Jump 'N Jack has 24 patented, teeth-cleaning Dental Ridges which can be filled with Kong's tasty and easy-to-use Stuff 'N Pastes, or other treats, relieving your dog of boredom when he's left alone. These Dental Ridges make the Jump 'N Jack a fun and effective dental toy. The Jump 'N Jack also has an unpredictable bounce that is irresistible to dogs, and is great for a game of fetch. Medium 3.5 inches, Small 2.75 inches.