One of the four tennis tournaments in the US Open....

One of the four tennis tournaments in the US Open.
The day before the game you can watch players' practice free of charge.
However, since you can not bring in big baggage (rucksack etc), you have to deposit it with $ 5 for a security check.
The seats are also free, you can sit in the front row seats where you can not sit normally and you can feel the players close up, and you can take pictures as well. Flash is strictly prohibited.
Players may respond to the sign after practice.