Thank you. 50 used hard tennis balls. How about using them for baseball or soccer practice? They should still be usable 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 lint attached. ◆ For baseball: tee practice, long tee practice, and free batting practice in a small space. ◆ For soccer: shooting and juggling practice. (They seem to be effective for training to hit the core of the ball because they are small) Elementary school students in the lower grades are often afraid of the ball when they first join a team. This is probably due to the fear of "it hurts when it hits you." Using tennis balls (which are similar in size), catch ball and fielding practice with bare hands. The pain will be reduced even if it hits you. (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 We will use recycled cardboard boxes for packaging. Please refrain from purchasing if you are concerned about the condition. Please enlarge the photos and check them carefully, and only purchase if you understand.