Seiko in-house caliber 9S65A found in a Grand Seiko automatic watch. This caliber was released in 2010 and is essentially an upgrade from GS cal. 9S55 which offered a lower 48 hr power reserve. The 9S66 found in the limited edition GMT has a blue titanium/tungsten rotor featuring a Grand Seiko lion crest. The Spron 610 hairspring is anti-magnetic. This Grand Seiko movement is rated to be accurate within -3/+5 seconds/day.