Seiko VK64A

The Seiko caliber VK64A is a quartz mecaquartz chronograph movement manufactured in Japan. It combines quartz timekeeping with a mechanical module for operating the chronograph functions, resulting in a smooth sweep seconds hand rather than the stepped ticking typical of pure quartz chronographs. The bi-compax layout places subdials at 3:00 and 9:00 with a date window at 6:00. Accuracy is rated at ±20 seconds per month, and the movement uses an SR936SW battery with an approximate 36-month life. It remains in production and is used by various fashion and microbrand watchmakers.