Soccer ball
Especially at the younger ages players should write their first name prominently in several places on the ball. This helps coaches learn names quickly.
u6: Size 3
u8: Size 3
u10: Size 4
u12: Size 4
u14-u19: Size 5
u6: Size 3
u8: Size 3
u10: Size 4
u12: Size 4
u14-u19: Size 5