Get these  Replacement Plastic Balls and exchange your old ones out for new ones.  It comes in a convenient eight-pack to provide you with plenty to use during practice.  The 70mm size is ideal for trying out your hitting skills.  The plastic material won't go too far so you can gather them up for multiple uses.  Place the Franklin plastic baseballs in one of the pitching machines from this same brand. 
  Kids Toy Baseballs - 8 Pack Solid Plastic Balls:
PERFECT FOR BATTING PRACTICE: Solid mold construction ensures optimal flight paths and distance so you can hit the ball harder and farther
LIGHTWEIGHT AND SAFE: The lightweight construction and perforated exterior ensure comfort and safety for younger players
OFFICIAL SIZE: The balls are 70mm in diameter to mimic the size of real baseballs, giving hitting an authentic feel
FUN FOR ALL AGES: These plastic baseballs are great for backyard games, batting practice, and everything in between for baseball players of all ages
COMPATIBLE WITH FRANKLIN PITCHING MACHINES: These balls are designed to be used with  pitching machine item numbers 6696S3 and 14912

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