GAMMA Revolution Foam Balls are low compression, medium bounce balls designed for kids learning to play tennis and experienced players training or warming up. Revolution foam balls have a Magnacore that offers a consistent bounce similar to a standard construction tennis ball. Revolution Balls are approved by the USTA for the QuickStart Tennis format on a 36 foot court and they conform to the ITF Stage 3 specification. 3 Pack >>$5.90 12 Pack>>$35.99 60 Pack>>$125.99