There are literally dozens of different brands of dimpled balls on the market, and they are NOT all the same.
A regulation leather baseball has a hardness of about 90 (Rockwell A scale) when new. BATA Dimpled Balls have a hardness of about 84. Some dimpled balls (other brands) are as soft as 50. Bata pitching machines are designed and calibrated to pitch Bata dimpled balls and regulation leather balls. You’ve just spent a lot of money on a pitching machine, and buying balls at your local store to save $5 on a dozen balls might not be a good idea. Your best bet is to use balls that are proven to provide quality results with the machine that you purchased. BATA Dimpled balls pitch very well in BATA machines; therefore, we recommend that you use BATA Dimpled balls in your machine (or regulation, high-quality leather balls. Low seams are better than high seams).
Be aware that ANY seamed ball run through any wheeled pitching machine will have the possibility of presenting a knuckleball to the batter. This possibility is greatly reduced when using low seamed balls.