Penn Championship Tennis Balls - Extra Duty Felt Pressurized Tennis Balls Penn Championship Extra Duty Felt, Yellow Tennis Balls. America?s #1st Selling Tennis Ball. Penn Championship is the Official Ball of USTA Leagues. It Features a Controlled Fiber Release for Consistent Nap, Natural Rubber for Consistent Feel and Reduced Shock. Interlocked Wool Fiber for Longer Wear. Brand New, Unused Championship Balls are Great for Play on Hard Tennis Courts. They come in Cans and Each Can Contains 3 Yellow Balls. AMERICA'S #1 SELLING BALL: The product of 100 years worth of testing and perfecting; Penn Championship is the best selling tennis ball in America. PENN PERFORMANCE: Controlled fiber release provides perfectly even nap, while natural rubber offers consistent feel and reduced shock. The Championship line provides unparalleled consistency every time you hit the court. ALL COURTS: While extra duty tennis balls are best suited for hard court matches, they can also be played on all indoor and outdoor softer, clay court surfaces as well. OFFICIAL BALL: Penn Championship is the Official Ball of USTA Leagues, so you know you're playing with high quality and consistent ball. Available in extra-duty felt, regular duty felt, or extra-duty high altitude felt. USTA and ITF approved. LASTING DURABILITY: Interlocked wool fiber ensures the all courts tennis balls will play like new for as long as possible. In stock and ready to ship FAST!!!