The patented secret with micro cell construction balls is the inner core which is powered by 700 million air-filled micro cells. These do not escape through the rubber core resulting in a highly playable ball that does not lose bounce and performance over time. Tretorn micro cell balls are equally suited for the frequent competition player as the occational recreational player. Simply the best choice for the majority of players. Unaffected by altitude level and temperatues, micro cell technology balls perform excellent also in higher altitudes and colder climate conditions.