SIZE: Available in sizes 4 and 5. This reaction training ball can be used by soccer goalkeepers and field players alike. It has countless training uses to improve your overall soccer performance. BLADDER: Butyl bladder to retain maximum air pressure and shape. This long-lasting bladder can hold air for an extended period of time ensuring perfect shape. MATERIAL: New and improved PU outer material with hand stitched panels. This material is softer to the touch and feels more like a premium soccer ball. The meticulous manufacturing process ensures a durable product that can be used for years! WEIGHT: Keeperstop has reengineered the weight inside the ball to be softer, lighter and provide even more erratic movement. The ball is weighted in one panel to cause irregular movement both on the ground and in the air when it is thrown or kicked. As the ball travels, spins and rotates, the weighted panel will cause the ball to move in irregular ways to help train the goalkeeper or soccer players hand eye coordination and reactions. USE: The ball can be used for training and coaching sessions by goalkeeper or field players. The irregular movement works the goalkeepers reactions, speed and agility. The ball is a great training tool for improving hand eye coordination. This training ball is ideal for hand services but can also be kicked to provide more game like training situations. The new outer material and softer inner weight makes it easier to strike the ball as you would a normal game ball.