Ready Set Fetch! Give your dog something to jump for. Extra tennis balls that are high quality and designed for the game of fetch. Extra Thick Rubber Core. High quality tennis balls. Attractive colors with improved visibility! Perfect for exercising your dog! Use it in the park, in your backyard or anywhere there is plenty of room. Can be used alone or with the ChuckIt! Ball Launchers. High visibility two-tone ball. Extra wall thickness.