Official Water Polo Ball of USA Water Poo Water reactant grip for control Hand buffed for added grip Precision wound nylon carcass Size 3 The Official ball of USA Water Polo and LEN European Aquatics which governs 54 Countries. KAP7 is trusted by the top water polo experts in the world. Play with the Official Ball of the LEN. KAP7 has tapped into years of experience, proprietary technology, and the highest quality materials to develop the HydroGrip Ball. It is the best and longest lasting ball in the world. The HydroGrip has been designed to meet guidelines for local, national, and global specifications.