Gamma Green Dot 78 Tennis Ball - Box of 48 From kids learning to master the game to experienced players practicing advanced skills, the GAMMA 78 Green Dot Tennis Balls are a great option for improving tennis techniques. The 78 Green Dot ball is USTA approved for 10 and under tennis tournament play and also ideal for Ages 11+ and adult beginners on a 78' court. These lightweight tennis balls feature a low compression core making them 25% slower than a standard tennis ball and providing a lower bounce. Players are able to get into position and react to hit the ball more effectively. Numbered 1-3 for tournament play. USTA/ITF Stage 1 specification.