It has been 25 years since Grand Seiko produced the first highly accurate Caliber 9F quartz movement, and it has been viewed as a cult classic ever since.
The movement was designed to set new standards of durability and precision for watches with the opulence and prestige of the Grand Seiko marque.
A 25th anniversary timepiece was unveiled at Baselworld, but this month the Japanese watchmaker has released a GMT traveller that will also have the same precision rate of +/- 5 seconds per year.
An innovation with the movement, named the 9F86, is that it keeps core time in minutes and seconds even when the hour hand is adjusted.
The Caliber 9F86 is used in one limited edition anniversary edition of 800 units priced at £3250 and arriving in October, and two other permanent creations in the Grand Seiko Sport Collection.