The silicon escape wheel for a Swiss lever escapement, that is lightweight, hard, anti-magnetic, highly corrosion-resistant, true to shape than any steel wheel, and above all, its locking tooth faces never need to be lubricated. The limited special version of the Annual Calendar Ref. 5250 presented in 2005 was the first Patek Philippe watch with silicon-based technology.
The Spiromax® balance spring made of a silicon-based material, a patented invention that improves the isochronism of mechanical watches. A second limited edition of the Annual Calendar Ref. 5350 has been presented in 2006, this time with the Spiromax® balance spring in Silinvar™.
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