Chuckit! Tennis Ball XLarge 2pk | Shrink SleeveChuckit! Tennis Ball XLarge 2pk Shrink Sleeve Chuckit! Tennis Balls are made of high quality materials and specifically designed for the game of fetch. Constructed of a natural rubber it features an extra thick rubber core and durable material that floats in water. The bright colors provide improved visibility when playing with your dog and help to prevent the ball from being lost. Use alone, or with your Chuckit! Launcher (sold separately).