Zenith A386 El Primero Movement

The A386 uses the El Primero 3019 PHC high-beat movement, with 36,000 vibrations per hour (5 hz) permitting measurements to the tenth of a second, which at time of release (1969) compared to the competing Caliber 11 at 19,800 and Seiko 6139 at 21,600, and the standard 18,000 vph (2.5 hz, measuring to a fifth of a second).

Higher frequency brings greater precision, with fewer variations in rate due to external factors. Zenith compensated for the watch losing power more rapidly due to its high beat by incorporating a mainspring with 50-hour power reserve.

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