In 2017, Patek Philippe unveiled its fifth ?Advanced Research? limited-edition timepiece, and it was not just a showcase for two technical innovations but also an anniversary piece for the brand?s sportiest collection: The Patek Philippe Aquanaut celebrated its 20th anniversary in 2017.

The watch that commemorates this milestone ? the Ref. 5650G Aquanaut Travel Time ?Patek Philippe Advanced Research? ? has an 18K white-gold case measuring 40.8 mm in diameter and 11 mm thick and is water-resistant to 120 meters. It is equipped with the dual time-zone function that Patek has used in previous models such as the Calatrava Pilot Travel Time and Nautilus Travel Time, and its self-winding movement features, for the first time, two major technical innovations:
A new Spiromax® balance spring made of Silinvar; apart from the patented terminal curve (Patek Philippe boss at the outer end), its geometry now also features an inner boss near the integrated collet. It improves the isochronism of the balance in the vertical orientations of the watch. As a result, its rate accuracy ranges between -1 and +2 seconds per day ? similar to the precision of Patek Philippe?s tourbillon watches.
A compliant (flexible) mechanism crafted from conventional horological steel that is used to set the second time-zone. This device, which is composed of only 12  filigreed steel parts with several intersecting leaf springs ? as compared to the 37 parts used in the more traditional mechanism ? tran...