Our mini tennis balls are ITF-approved and designed specifically for the physical size & strength of young players. Mini tennis balls are larger & lighter than senior balls, making them easier to hit for a much more enjoyable introduction to the sport. For example, Stage 3 red mini tennis balls are designed for children aged 8 & under. Larger, softer & slower than regular tennis balls, they also bounce lower, giving smaller children the opportunity to hit groundstrokes, which is often impossible with a regular tennis ball. As children progress from Stage 3 mini tennis balls to Stage 2 orange tennis balls & Stage 1 green tennis balls, the balls incrementally become heavier & smaller. Foam tennis balls are also a great choice for children as they are light, soft & larger than regular balls.