Thank you. 50 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. They seem to have been used for about a month at a tennis school. There is some fine thread debris attached. ◆ Baseball: Tee, long tee, and free batting practice in a small space. ◆ Soccer: Shooting and juggling practice. (They seem to be effective for training to hit the core because they are small) Elementary school students in the lower grades are 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), Catching and fielding practice with 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. The impact on the body is less because of the light weight. ※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 Recycled cardboard boxes will be used for packing. Please refrain from purchasing if you are concerned about details. Please enlarge the photos and check them carefully, and only those who understand are welcome.