In order to accommodate months with 31, 30 and 28 days, and february 29 in leap years, a movement must have a mechanical “memory” of four years – or 1,461 days. This function requires a highly sophisticated mechanism, based on a complex system of levers and cams pivoting around their axes. This is a domain in which Patek Philippe has repeatedly leveraged its long-standing competence.

Watch
Ultra-thin mechanical self-winding movement. 
Caliber : 240 Q. 
Dial: Silvery-white opaline, gold applied hour markers.
Case : Rose gold. 
Case diameter: 35.1 mm. 
Thickness: 8.7 mm. 
Water resistant : 30 m. 
Sapphire crystal case back.
Gemsetting : Bezel set with 68 diamonds (~0.68 ct). 
Prong buckle set with 27 diamonds (~0.2 ct).
Straps : Shiny alligator with square scales, hand-stitched, mink gray (originally fitted) and royal purple (additional strap). 
Prong buckle set with 27 diamonds (~0.2 ct).
Perpetual calendar. 
Day, date, month, leap year and 24-hour indication by hands. 
Moon phases. 
Diameter: 27.5 mm. 
Thickness: 3.88 mm. 
Number of parts: 275. 
Bridges: 8. 
Jewels: 27. 
Winding rotor: 22K gold off-center minirotor. 
Frequency: 21’600 semi-oscillations/hour (3 Hz). 
Power reserve: min. 38 hours, max. 48 hours. 
Balance: Gyromax®. 
Balance spring: Spiromax®. 
Hallmark: Patek Philippe Seal.