KONG Blue's are 25% stronger than regular KONG toys (in excess of 3800 psi). They can also be stretched up to 9 times their original length and they're highly puncture resistant. 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. Puncture resistant, bouncy, and chewer friendly. Satisfies a dog's natural need to chew cleans teeth and conditions gums. Thick, flexible walls that keep springing back for more! Non-toxic, nonabrasive, non-splintering, and does not get sharp when chewed. Recommended by veterinarians, trainers, dog professionals and satisfied customers world wide.