As the official ball of the US Open since 1978, these tennis balls deliver top-of-the-line feel, performance, and quality. They are specially constructed for long-lasting performance and increased playability across all levels of play. Each ball is made with a premium tex/tech industries felt cover for responsive feedback with every stroke. Extra-duty line of tennis balls for optimal performance on hard courts. Approved for USTA and ITF competitive play. Available in Cans of 3.