Designed for the most demanding use, the Chuckit! Ultra Ball is not your dog's ordinary ball. Simply put, this is the best ball for the game of fetch. Developed to have high bounce, high buoyancy, high visibility and high durability. The Chuckit! Ultra Ball promises to outplay the ordinary. Compatible with Chuckit! Launchers. These top-selling balls are available in sizes small, medium, large, x-large and xx-large. Medium size is for a 2 pack.