Official Ball of the Australian Open (AO) The official ball of the Australian Open, the Dunlop Australian Open tennis ball provides the ultimate in performance and durability for championship-caliber play. Trusted for the first Grand Slam tournament of the year, the Dunlop Australian Open tennis ball delivers high-quality performance for the best players in the world. Featuring a re-mastered HD Core and HD Pro Cloth, these tennis balls maintain their brightness and playability for long-lasting tennis play at the highest levels of competition. The Dunlop Australian Open (AO) Balls contains 3 balls per can. Tennis Balls 601354-Can