Thank you. 50 used hard tennis balls. How about using them for baseball practice? They should still be usable for tennis practice, but I don't know the manufacturers in detail. There is some fine thread debris attached. For tee practice, long tee practice, and free batting practice in a small space. Please enlarge the photos and check them carefully. Young elementary school students 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), 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 The packaging box will be a long, recycled cardboard box. Please refrain from purchasing if you are concerned about the condition. Please enlarge the photos and only purchase if you understand the condition.