I bought 100 of these iPong training balls along with my iPong topspin robot. Havent tried the robot yet.
IMO, I find about 50% of the 100 balls have that uneven line at the half dome.
No 2 star label on the ball itself like advertised but its pretty hard when I press my thumb on it (feels like 2 star)
Paid $20 for 100 balls.