Wilson Sporting Goods Hope All Court Extra Duty Tennis Balls Rubber Wilson is the Official Ball of the US Open and the Australian Open Grand Slam Championships With the purchase of this product, Wilson makes a donation to the Breast Cancer Research Foundation (BCRF) to support research for a cure for breast cancer Extra duty ideal for longer play on hard court surfaces Exclusive Dura-Weave felt from Wilson provides greater durability and improved performance Ideal ball for high school and recreational players as well as tournaments and fundraisers