Kixsports Primus Performance Soccer Ball Size 4 & 5 - Club Level Ball for Higher Level Soccer Training & Match Play Stitching - Hand sewn with 5-ply twisted polyester cord for maximum durability Cover - Polyurethane (PU) casing provide durability and minimizes moisture absorption Backing - Cotton/polyester backing improves durability and touch Bladder - Butyl rubber bladder gives longer air retention while providing better responsiveness Pattern - Black and gold rings help read the ball better in flight and identify spin