The NCAA Women's and High Schools Girl's Official KAP7 Size 4 HydroGrip Water Polo Ball has quickly become the go-to choice for amateur and elite water polo players alike. 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.