These tennis balls are specifically designed for highly-skilled and recreational players competing on asphalt or in the gym. The Hard Court Championship Series tennis balls are made of premium-grade rubber and felt to deliver unmatched performance on indoor and outdoor hard court surfaces. Each ball is engineered with Durafelt technology which provides long-lasting playability and an unmatched feel. The fluorescent green coloring makes the balls highly visible so players can react quickly on returns. Available in a Can of 3.