The PATIKIL Bounce Reaction Balls are designed to enhance hand-eye coordination and agility. Made from high-density thermoplastic rubber (TPR), these durable balls are suitable for use on hard surfaces such as grass, wood, stone, asphalt, clay, and mud. The hexagonal design and grainy surface provide a good hand grip and cause the balls to bounce unpredictably, making them ideal for training in various sports including baseball, soccer, softball, basketball, table tennis, ping pong, tennis, and badminton. The set includes four blue reaction balls, each measuring 47 x 47 x 55mm (1.85 x 1.85 x 2.17 inches). These balls can be used for both individual and group training sessions, indoors or outdoors.