Thank you. 100 used hard tennis balls. How about using them for baseball or soccer practice? They can still be used for tennis practice, but I don't know the manufacturer. There is some fine thread debris attached. ◆ For baseball: tee practice, long tee practice, and free batting practice in a small space. ◆ For soccer: shooting and juggling practice. (I think it's effective for training to catch the core because they are small) Please enlarge the photos and check them carefully. Elementary school students in the lower grades are often afraid of the ball when they first join the team. This is probably due to the fear of "it hurts when it hits you." Using tennis balls (which are similar in size), You can do catchball and fielding practice with your bare hands. The pain will be reduced even if it hits your body. (Please be careful of finger injuries!) Batting practice such as tee and long tee. Because of the light weight, the impact on the body is less. ※For reference [Hard Tennis Ball Standards - From Wikipedia] Diameter (mm) 65.4～68.6 Weight (g) 56.0～59.4 [Elementary School D Ball Standards - From All Japan Soft Baseball Federation HP] Diameter (mm) 64.0～65.0 Weight (g) 105.～110 [Elementary School J Ball Standards - From All Japan Soft Baseball Federation HP] Diameter (mm) 68.5～69.5 Weight (g) 127.2～130.8 I will use a tall recycled cardboard box for packing. Please refrain from purchasing if you are concerned about the condition. Please enlarge the photos and only purchase if you understand the condition.