The split-seconds chronograph is one of the three most difficult complications to master, alongside the tourbillon and the minute repeater. It takes a highly sophisticated mechanism to control the two chronograph hands, one of which may be stopped to measure an intermediate or lap time or retain a reference time while the other continues its course unaffected, even by fractions of a second. When released again, the split-seconds hand instantly catches up with the primary hand and the two stacked hands move on together.
Split-Seconds chronograph. Instantaneous 30-minute counter. Perpetual calendar. Moon phases. Day, month, leap year and day/night indication in apertures. Date by hand. Seconds subdial. Dial: silvery opaline, applied gold hour markers with luminescent coating. 18K gold dial plate. Alligator strap with square scales, hand-stitched, shiny chocolate brown, fold-over clasp. Fold-over clasp. Case: rose gold. Interchangeable full back and sapphire-crystal case back. Water resistant to 30 m. Case diameter: 40.2 mm. Height: 14.3 mm.
Split-seconds chronograph, 30-minute counter. Perpetual calendar with day/night indication. Diameter: 32 mm. Height: 8.7 mm. Parts: 496. Bridges: 12. Jewels: 34. Power reserve: With the chronograph disengaged: min. 55 hours - max. 65 hours. Balance: Gyromax®. Vibrations/hour: 28 800 (4 Hz). Balance spring: Breguet. Hallmark: Patek Philippe Seal.