Grand Seiko 9R66

The Caliber 9R66 is Seiko's automatic Spring Drive movement with GMT function, introduced in 2007 and based on the 9R65 caliber. It delivers ±15 seconds per month accuracy through Spring Drive's continuous glide motion, paired with a 72-hour power reserve. The movement features a power reserve indicator and dual time display via a 24-hour hand, with 30 jewels for smooth operation. It remains in production.