S. Epson Caliber YN84

Brand	S. Epson (Seiko)
Caliber Number	YN84, YN84A
Movement Type	Automatic, self-winding mechanical
Diameter	27.4mm
Height	5.32mm
Jewel Count	22
Beat Rate / Frequency	21,600 bph / 3 Hz
Lift Angle	52 degrees (unconfirmed)
Power Reserve	40 hours
Hand-Windable?	Yes
Anti-Shock Device	Diashock
Hand Count	5
Functions	Central hours; central minutes; central sweeping seconds; fan style power reserve indicator at 12:00; 24 hour indicator at 6:00; open balance wheel at 9:00
Hacking Seconds?	Yes
Country of Manufacture	Made in Japan
Known Models	Vostok Europe Expedition (Ref: YN84-597A543), Master Works Quattro / 001 (Ref: MW08SI1-GCBKG81) (Add your watch to the comments below…)

The S. Epson caliber YN84 is an automatic movement with a power reserve indicator and a 24 hour subdial.

The YN84 is also capable of displaying an open balance wheel at 9:00, although not all watches powered by this movement will have the cutout for it.

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