Street Tennis Club Packs of 15 Tennis Balls for Kids/Juniors. Red 36' inch starter balls ages 3-7.(yellow/red) Quick kids 36 tennis balls conform to the USTA quick start tennis format and ITF Stage 3 standards Proper ball and racquet helps develop stroke mechanics and technique. These balls are larger and softer than standard yellow tennis balls, with a lower bounce Players ages 3-6 will contact the ball twice as often when using the right color ball Research shows that a childs first sports experience can shape his or her attitude towards sports for the rest of his or her life