Penn Championship tennis balls represent the standard by which all other tennis balls are measured with consistent feel and playability every time you step onto the court. They feature a controlled fibre release for consistent nap, natural rubber for consistent feel and reduced shock, and interlocked wool fibre for longer wear. Penn Championship is the Official Ball of USTA Leagues. They are USTA and ITF approved (USTA National Campus, 2019) and is available in extra-duty felt, regular duty felt, or extra-duty high altitude felt. The Championship Line provides quality play every time you hit the court. Penn Championship tennis balls are made for different surfaces. Extra-Duty felt for hard courts, Regular-Duty for softer courts (clay, grass) and Extra-Duty High Altitude for courts located in higher elevations (4000+ feet above sea level). Penn Championship is the Official Ball of USTA Leagues. (USTA National Campus, 2019) Deep-Elastic seams for increased durability, and a consistent bounce. Available in several bulk case sizes up to 24 cans with 72 tennis balls total. Penn celebrated 100 Years of Excellence in 2010. Starting in a small town in Jeanette, Pennsylvania in 1910.