The Seiko caliber 8R28 (aka 8R28) is an in-house automatic chronograph movement with 34 jewels, a power reserve of about 45 hours, and beats at 28,800 vph. As part of the 8R family of movements, the 8R28 features a vertical clutch and column wheel chronograph system. This movement is entirely made in Japan.
Average Accuracy Rating:
What can you expect as far as timekeeping?
Seiko official documentation claims that the average accuracy of the 8R28 is between -15 to +25 seconds per day in normal operating conditions and temperatures of 5C to 35C (41F to 95F).