Seiko 8T63

Cal. 8T63 is a Japanese quartz chronograph movement introduced by Seiko in 2015 as an evolution of the 6T63 caliber. It maintains an accuracy of ±15 seconds per month, uses an SR936SW battery with an approximate 36-month life, and contains no jewels. The movement incorporates a mechanical chronograph module featuring a one-piece three-pointed reset hammer derived from the 8R28, which provides greater durability than typical Swiss designs, along with a self-alignment function that returns all counter hands to zero instantaneously. The chronograph can measure up to 60 minutes in one-second increments. Cal. 8T63 remains in production.