The third notable debut: one of the biggest successes of the manufacture in a totally new version is the new Ref. 4947/1A-001 Annual Calendar. The very first version of this queen among useful complications with a round case in steel and a metal bracelet. Patek Philippe invented the ingenious Annual Calendar mechanism that was patented in 1996. It requires only one manual correction per year and so far has been available in various ladies’ and men’s models in three gold colors and in platinum.