I purchased 144 double fish practice balls from Hi-Qua Sports. They are all pretty spherical, with an occasional oblong ball. These balls are great for service practice, when tend to brush the ball more than strike it. These balls tend to crumple more easily, however, and compress when struck flatly. This makes the ball seem dead, with less bounce. Again great for service because the focus is usually on spin during service. These can also be used for looping, it will help you distinguish a good brush stroke from a more flat hit by witnessing the difference in feel, sound, and bounce when the ball is compressed, ie. hit flatly instead of brushstroked. I paid 25 dollars plus about 5 dollars shipping, so 30 total for 144 balls. Not a bad deal.