Rolex introduced its first automatic perpetual caliber 620 in 1931, commercializing its new self-winding patents. It would then use the cal. 620 in the First Series Bubblebacks produced until 1935,
link starting with reference 1858. Over the years, Rolex updated the
link 600 series with newer calibers to improve accuracy, reliability, and durability after
link the original perpetual movement.
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