A ref. A386 El Primero, a technical masterclass in movement design, Zenith’s calibre 3019 PHC was not just amongst the earliest automatic chronographs ever, but a high-beat and far thinner than any competitor. This example is a Mark 3, produced in 1971, and is very well-preserved. It features sharp lug bevels and top brushing, its original Gay Frères ladder bracelet, and original ‘A under H’ dial with gorgeous cream tritium.