Dunlop tennis balls are engineered to meet the most exacting demands of both the recreational and serious player. TheirFort Clay Court tennis ball features an HD Core plus innovative Clay Guard cloth technology for added durability during tournament level play. The cloth itself has been treated to repel clay particles so the ball stays brighter longer, making it easier to see. It’s no wonder the Fort Clay Court ball is the official clay court ball of both the ATP and WTA! ITF approved.