when it was launched, indeed Moritz.
But I would say that when being that slimm, the most important is then to manage to keep it accurate and reliable. What Patek's caliber has shown.
Can I correct something Moritz, it seems to me the 5959's movement is equipped with the isolator feature.
It is indeed a fantastic chronograph movement and it also very well fits with the 5950 and his thin cushion shaped case as it alows the 5951 (+ Perpetual Calendar) to remain elegant as it is slim.
Cheers, Mark