Since 2005, Patek's Advanced Research Program has been experimenting with components made of silinvar, and has over the years produced a handful limited edition watches containing various such components. The components are the Spiromax balance spring, th...
So in other words, there have possibly been some sort issues with the other components and they are still working to solve those. I find these Advanced Research pieces very interesting and wish they would put out a few more and make them more easily acces...