it was a Perpetual Calendar, unless to say not that easy to design and to produce : The first years, only a few (to 4 to 5) per year were produced.
The Classic was obviously much more easy on the mechanical point of view .
The Goldpfeil was another challenge as it was an (almost 10O %) in-house movement and it was to be produced on a quite large number (in comparison with our standard) : 175 movement were produced within 18 months.
This gave us experience for our last challenge the Trio which is also an (almost 10O %) in-house.
You may notice that I am not talking about Opus 3 which is a very, very special case
