Dog toys KONG® CrunchAir™ Balls - the tennis balls with a difference. KONG® CrunchAir™ Balls make a crunching sound when bitten, which excites dogs and encourages them to play. At the same time, their natural chewing and hunting instincts can be satisfied. KONG® CrunchAir™ Balls have a strong bounce that is perfect for interactive play. Their durability ensures even longer lasting games of fetch, catch and chew. What's more, KONG® tennis material is specially formulated to be gentle on teeth and gums, allowing dogs to enjoy carefree play. Note: Please never leave the pet unattended while playing. No toy is indestructible. To prevent injuries, the toy should be checked regularly for damage or loose parts and replaced if necessary.