Product Description Unbeatable performance, unmatched consistency and the most premium woven felt all add up to more W's for you. Wilson is used at more than 45 professional tournaments worldwide. That's why we are played at more majors than any other brand. Wilson, the Official Ball of Australian Open, US Open, Davis Cup and the Fed Cup. Dura-Weave felt lends long-lasting durability Extra Duty: Ideal performance on hard, abrasive courts Regular Duty: Ideal performance on soft, clay/indoor surfaces High Altitude: Ideal performance on surfaces above 3,000 ft. Can includes 3 balls Balls are numbered to differentiate from balls used by other players on neighboring courts