Penn Championship Extra Duty Tennis Balls (16 Cans) The Penn Championship Extra Duty Tennis Balls are the official ball of USTA League Tennis. For use on hard tennis courts, the regular duty balls are built with natural rubber for reliable feel and reduced shock. The interlocked wool fiber composition increases durability for longer wear, while deep-elastic seams offer reduced cracking. This 16 can multi-pack provides the gear you need to be a champion from one season to the next. Features: 16-pack (48 tennis balls) Extra Duty tennis balls for use on hard courts Official ball of USTA League Tennis and the standard by which all other tennis balls are made Interlocked wool fiber for longer wear Deep-elastic seams for reduced cracking Reliable performance Setting the bar high for all other tennis balls, the Penn Champ Tennis Balls come three to a can, so in this pack of 16 cans you get 48 balls. With so many, you don't need to worry about running out, meaning you can keep your mind on your game!