This drawstring mesh bag has a total of 18 pressure-free tennis balls. Weight: 55.0-58.50g/pc, Diameter: 65.4-68.6mm; Deformation: 0.22-0.29 inches, Rebound: (20 degrees): 135-145 cm. These tennis balls are suitable for all court surfaces. Also, great for kids' outdoor play and training dogs to fetch balls. Hours of entertainment on and off the court, great for all ages and athletic dogs. 18 Tennis Balls Kids love these too Storage Bag with Tennis Balls Suitable for all court surfaces Great for athletic people and dogs Pressure-free