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.
Dial: white opaline, hand-guilloched center, black Roman numerals. White gold. Case: white gold. Case diameter: 38 mm. Height: 11.8 mm. Water resistant to 30 m. Sapphire-crystal case back protected by a hinged dust cover. Strap: matte dark brown alligator. Fold-over clasp. Perpetual calendar with retrograde date hand. Day, month, leap year in apertures. Sweep seconds hand. Moon phases.
Perpetual calendar with retrograde date hand. Diameter: 28 mm. Height: 5.35 mm. Parts: 361. Bridges: 9. Jewels: 30. Power reserve: Min. 35 hours - max. 45 hours. Central rotor in 21K gold, unidirectional winding. Balance: Gyromax®. Vibrations/hour: 28 800 (4 Hz). Balance spring: Spiromax®. Hallmark: Patek Philippe Seal.