Seiko EPSON-YM90A

The S. Epson caliber YM90A is a quartz chronograph movement manufactured in Japan. It uses an SR927SW battery with a quoted life of approximately five years when the chronograph function is used sparingly. The movement features a simple stopwatch layout with a central seconds hand and 60-minute counter, notably lacking a running seconds hand. This caliber powered the Yema Spacegraf Zero-G, introduced in 2020 as a collaboration with France's CNES space agency to mark the 30th anniversary of French micro-gravity simulated flights.