The Grand Prix tennis ball features a specialized rubber core formula, consisting of 14 ingredients, combined with the finest woven felt for an incredible feel. The MaxGlo felt featured on these tennis balls is 14% brighter than regular cloth, giving players the high-quality visibility. The balls have been specifically engineered to withstand the harsh impacts on hard courts. However, are also available in the regular duty line for use on all surfaces including clay and indoor courts. Both products are approved for UTSA and ITF tournament and league play. Available in a Can of 3.