Chuckit! Air Fetch Ball Dog Toy, Medium (2.5 Inch Diameter), for dogs 20-60 lbs, Pack of 2Air Fetch Dog Ball: These high performance balls for dogs have a hollow, mesh like design that helps facilitate breathing and airflow into your dog's lungs while running and fetching; a breathable alternative to standard tennis balls Run Further, Fetch Longer: Chuckit! Dog Fetch Balls are compatible with Chuckit! Dog Ball Launchers. Can also be used as a treat toy for dog training by utilizing the openings to stuff dog treats inside. Also floats for