Features Enter your model number to make sure this fits. P.when("ReplacementPartsBulletLoader").execute(function(module){ module.initializeDPX(); }) Penn's longest lasting tennis ball. LongPlay felt for extended play Smart Optik felt for optimum visibility 3 balls per can / 24 cans per case This listing is for 1 case (24 cans) Description The Pro Penn Marathon is Penn's longest lasting tennis ball. Features Encore Technology for 22% longer lasting core, high tenacity LongPlay felt for extended play, and Smart Optik felt for optimum visibility. Pro Penn Marathon balls are the choice of USPTA pros due to its durability, longevity, and visibility. Convenient case for frequent players.