Case material: Rose gold; Charge: Automatic; Conditions: Excellent Presentation condition : With dealer guarantee ; Model: Complications Annual Calendar Price on request Gmtbroker Reference: 5350R-001 LIMITED TO ONLY 300 PIECES WORLD-WIDE: PATEK PHILIPPE 5350R ADVANCED RESEARCH ANNUAL CALENDAR IN ROSE GOLD 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. Isochronism is the key to every measurement of time based on any form of vibration. The greater the regularity of the vibration, the better the movement can be adjusted to achieve a high rate accuracy. If the source of the vibration is perfect, it is called isochronous. exhibition case back inscribed “Patek Philippe Advanced Research” with cyclops magnifier over the silicon escape wheel The first Patek Philippe watch with a Spiromax spring: the Ref. 5350 Annual Calendar in a limited "Patek Philippe Advanced Research" special edition A pioneering invention like the Spiromax spring deserves to be showcased. A second limited "Patek Philippe Advanced Research" edition of the self-winding Annual Calendar Ref. 5350