Seasoned Nautilus collectors know the 5990/1A-001 is more than the sum of its complications. Introduced in 2014, the grey-gradient dial echoes the slate decks of the original 3700 while accommodating travel-time apertures and a pointer date without disturbing the horizontal groove field. To make room for the +/- hour pushers, Patek re-engineered the watch into a three-part 40.5 mm case yet kept the profile to a trim 12.6 mm and preserved the 120 m water-rating—no small feat for a steel sports chronograph. The mirror-finished ‘ears’ now double as functional triggers, and the single 60-minute counter at 6 o’clock tidies what the 5980 left busy. Production halted in 2022 when the blue-dial 5990/1A-011 took the stage, turning the original anthracite variant into the insider’s choice for a steel travel-time chrono.