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The Encyclopedia of Horology

Calibre database

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Specifications

FieldSeiko calibre 9S55
MakerSeiko
CountryJapan (Shizukuishi, Iwate)
PeriodFrom 1998
Diameter28.4 mm
Height5.15 mm
Jewels26 jewels
Frequency28,800 vibrations per hour
Power reserveApproximately 50 hours
WindingAutomatic with manual winding and hacking seconds
SettingCrown setting with date quickset
EscapementSwiss lever with Seiko's own Spron hairspring material
BalanceJewelled, regulated to Grand Seiko's own accuracy standard
ComplicationsDate, Stop seconds
ArchitectureThe mechanical calibre with which Seiko resumed high-grade mechanical production at the Shizukuishi studio, assembled and adjusted by hand to an in-house accuracy specification stricter than the standard chronometer test.