" At First, these wristwatches have been 1-off or customized creations That always looked a whole lot like the pocket watches from which they evolved. But soon, wristwatches took by themselves aesthetic, with their own individual technical improvements to unravel new problems introduced by wrist-borne timekeepers. " Such as, should https://www.watchesworld.com/a-history-of-watch-reference-numbers/