X-small balls. The KONG AirDog Squeakair Ball combines two classic dog toys     the tennis ball and the squeaker toy     to create the perfect fetch toy. Our durable, high-quality Squeakair tennis ball will not wear down a dog   s teeth. It   s made with a special nonabrasive felt, compared to the abrasive material on normal tennis balls.  Perfect for games of fetch Squeaker to induce play Nonabrasive tennis material will not wear down your dog   s teeth