Wilson US Open Extra Duty Tennis Balls
This has been the official ball of the US Open since 1978 when the tournament moved from the West Side Tennis Club at Forest Hills to the USTA National Tennis Center in Flushing Meadows. The extra-duty ball plays very consistently straight out of the can. However, you may find that the bounce and feel of the ball subsides faster than you'd like.
Remember, in professional tournaments they bring in new balls after the first seven games, and then every nine games thereafter. So the pros are never hitting with what normal players would consider "used" tennis balls. Once you are in the second set, you’re using tennis balls that almost assuredly would have been swapped out in a pro match. If you are serious about the game, bring two cans to your match.