Originally Posted by coachrick
Unless things have changed, it's ambient air in most balls. Gamma used to put nitrogen to slow the pressure loss, but I don't know if that's what they do currently.
i thin you are right. it is liquid nitrogen
Babolat Pure drive 2012, 55 lbs, Kirschbaum Proline X / X-1 biphase. Nalbandian backhand and Nadal forehand.