In an NBA game, both teams use the same ball. There is no changing the basketball on a change of possession.
While this Mashable article says NBA uses 3 balls per game, according to Al Whitley, the Mavericks’ equipment manager for the past 14 years, “Unless there’s beer on it, or blood, or something unusual like that happens, it’s one ball for the whole game.”
The NBA has a system in place to make sure their ball always conforms to league standards. About two hours before the game, Whitley or another Mavericks staffer will take three balls to the officials’ room. The referees then use a gauge to make sure they are inflated properly. They also have a pump in their locker room.
NBA rules require ball to be between 7-1/2 and 8-1/2 pounds pressure.
Since 1983, the Spalding NBA Official Game Basketball has been the official game ball of the NBA. The ball features a full-grain leather cover that provides exceptional feel and touch, setting the standard for ultimate performance and playability. The ball is orange in color, 29.5 (749 mm) inches in circumference and weighs 22 ounces (624 g) (size 7).
Check out 10 Basketball Tips Guaranteed To Get You More Playing Time at Breakthrough Basketball.