The reference 5726/1A-010 represents Patek Philippe's integration of the annual calendar complication into the iconic collection designed by Gérald Genta in 1976, creating one of the most sophisticated and sought-after references within the sports-elegant Nautilus family through the combination of practical calendar functionality automatically accounting for 30 and 31-day months requiring manual correction only once per year on March 1st with moon phase indication and the distinctive porthole-inspired octagonal bezel design. Launched as the first stainless steel Nautilus to feature the annual calendar complication, this reference demonstrates Patek Philippe's commitment to combining technical complications with the sporty elegance that has made the Nautilus one of the most coveted collections in haute horlogerie since its revolutionary debut nearly five decades ago, appealing to collectors who value both complicated mechanical watchmaking and the timeless design language of integrated bracelet luxury sports watches combined with current-production availability backed by Patek Philippe's comprehensive warranty and global service network.

The 40.5mm case crafted in stainless steel features the signature Nautilus octagonal bezel with softly rounded edges and horizontal embossed pattern, brushed surfaces on bezel top and case band contrasting with polished chamfers highlighting the characteristic shape, hinged lugs integrated seamlessly into bracelet design, sapphire crystal, and transparent sapphire caseback revealing the meticulously finished movement. The silvery opaline dial displays applied luminous baton hour markers, black-oxidized gold hour and minute hands with luminous fill, recessed day and month display apertures in twin windows at 12 o'clock showing abbreviated day and month indications, moon phase display at 6 o'clock with realistic moon disk against blue starfield background showing lunar cycle with accuracy of one day's deviation every 122 years, date display at 6 o'clock beneath moon phase subdial, horizontal embossed pattern characteristic of Nautilus dials creating subtle texture across entire surface, minute track with printed minute divisions around outer edge. Inside beats the self-winding Caliber 324 S QA LU 24H featuring annual calendar mechanism with day, date, and month displays requiring single manual correction at end of February, moon phase complication, 24-hour subdial, central rotor in 21-karat gold, 34 jewels, Gyromax balance wheel, Spiromax balance spring in Silinvar silicon, frequency of 28,800 vibrations per hour, Patek Philippe Seal certification guaranteeing exceptional finishing and precision standards of minus three to plus two seconds per day, approximately 35 to 45 hours of power reserve. Stainless steel integrated Nautilus bracelet with brushed center links and polished outer links secures with fold-over clasp.

Reference Number: 5726/1A-010

Model: Nautilus

Movement: Automatic

Case Material: Stainless Steel

Bracelet Material: Stainless Steel

Dial: White

Case Diameter: 40mm

Year:

Condition:

Box & Papers: Original Box, Original Papers