The movement is really the interesting part here. The automatic caliber TH20-08 has hours, minutes, seconds, and yes, the date. But how did TAG Heuer make the chronograph run in such a strange way?
link My
link gut reaction was a snail cam. If the chronograph is functioning strangely by design, it's almost always a snail cam. And sure enough, there are actually two
link snail-shaped wheels, creating the decelerating motion for the central hand.