"Kong's exclusive black natural rubber formula is the world's strongest dog toy rubber! It's now being used by powerful chewers around the world like police K-9 teams, drug enforcement and military K-9 teams, AKC competition trainers, Shutzhund Clubs and more. It is puncture resistant, super bouncy, and chewer friendly. It is unmatched for resilience, durability, and bounce. Kong satisfies a dog's natural need to chew and also cleans teeth and conditions gums. The thick, flexible walls keep springing back for more! Kong rubber is non-toxic, nonabrasive, non-splintering, and does not get sharp when chewed. Kong toys are enthusiastically used and recommended by veterinarians, trainers, dog professionals and satisfied customers world wide."