Seiko spare part 565901 – Seconds heart-shaped drive for stopwatch caliber 9011 – NOS

Original Seiko spare part 565901 , classified as S-part 687 , from unused old stock (NOS).
This is the Heart Cam (seconds heart cam) for the Seiko 9011 stopwatch . This component is central to the reset mechanism of mechanical stopwatches and ensures that the second hand jumps exactly to zero when reset.
This part comes from long-term storage, is unused, and in excellent original condition. Due to the rarity of mechanical Seiko stopwatch parts, this component is particularly valuable to watchmakers and collectors.