It is possible that the flexible waterproof ball is made of materials such as nylon wand.Nylon is a kind of durable and flexible industrial polymers, and is used in the manufacture of a lot of products including sports .Peer (or nylon) is another type of polymer, which is similar to nylon in properties. It is characterized by its resistance to corrosion and impact, making it suitable for use in many applications.If you are looking for a flexible waterproof ball, nylon and indent can be good materials to achieve these properties. Waterproof coating can also be added to increase the effectiveness of protection of the ball against water.These spheres can be used in external activities or in water without being significantly affected by changing environmental conditions.