These Prince Play Stay 1 ITF & USTA Approved Low Compression Tennis Balls are specifically designed for 10 & under tournaments. They are 25% slower and 10% lighter than regular tennis balls, making them perfect for smaller courts and shorter, lighter racquets. These balls are suitable for all surfaces on 36 foot tennis courts and offer a great combination of quality, consistency, and durability. They are made in a two-tone color and are ideal for beginners, especially when teaching kids.