13ZN is the follow -up to 13.333 the first flyback Wrist watch in the world by Longines which was already the premiere producer of chronograph pocket watches in the world. Though th ose ha d 1 push button to set the stop watch function, the 13ZN added another push button, that is one at 2 to start and stop the second hand and minute hand function, while the push button at 4 to reset all the hands back to 12 or 0.
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