A year after the launch of the first Swiss lever escapement with a silicon escape wheel (patent application No. EP05006186), Patek Philippe presents an additional fundamental innovation: the Spiromax® balance spring made of Silinvar™. It is an epochal step forward in the constant quest for isochronism in portable mechanical watches. On the occasion of Baselworld 2006, the Geneva workshops will showcase the first watch with this innovation in a second limited “Patek Philippe Advanced Research” edition: the Ref. 5350 with a Spiromax® spring and a silicon escape wheel.