MIYOTA 8215

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The Miyota 8215 is a reliable, inexpensive, 21-jewel automatic watch movement manufactured in Japan by Citizen's Miyota division. [1, 2, 3]

Key Specifications

Type: Mechanical Automatic (with manual hand-winding)
Frequency: 21,600 vibrations per hour (3 Hz / 6 beats per second)
Power Reserve: Approximately 42 hours
Accuracy: -20 to +40 seconds per day
Diameter & Thickness: 26.00 mm diameter and 5.67 mm thick
Complications: Central hours, minutes, sweeping seconds, and a date window (typically at 3 o'clock) [1, 2, 3, 4]

Pros and Cons

Pros: Highly durable, easy to service, widely available for watch modding, and acts as a tough entry-level workhorse.
Cons: Features an indirect-drive second hand that can visually stutter or pause slightly when the watch is jolted. Older versions do not feature hacking (stopping the second hand to set the time), though modern iterations may include a stop-second device. Its uni-directional winding rotor can also spin freely and feel a bit loud or "rattly" on the wrist

This movement has been built into a (homage omega inspired seamaster 300 233) dive case.

100m water resistance.

Its OK for showering

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Very reliable.

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8205

The primary difference between the Miyota 8215 and the Miyota 8205 is their calendar complication: the Miyota 8215 features a date-only display, while the Miyota 8205 features a day-date display (showing both the day of the week and the date). [1, 2]

Both movements belong to Citizen’s rugged and affordable Miyota 8200 family and share the exact same core architecture, dimensions, and mounting specifications. [1, 2]

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Key Similarities

Frequency: 21,600 vibrations per hour (3 Hz / 6 beats per second). [1, 2]
Power Reserve: Approximately 42 hours. [1, 2]
Jewels: 21 jewels. [1, 2]
Winding: Automatic with uni-directional rotor winding and manual winding capability. [1, 2]
Accuracy Rating: -20 to +40 seconds per day. [1, 2]
Dimensions: 11.5 lignes (26 mm) in diameter and 5.67 mm in thickness. [1]
Hacking: Traditionally non-hacking (seconds hand does not stop when setting the time), though some modern revisions have featured hacking. [1, 2, 3]

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Key Differences

Feature	Miyota 8215	Miyota 8205
Complications	Date only (at the 3 o'clock or 6 o'clock position)	Day and Date display
Dial Layout	Cleaner, single calendar window	Wider or dual calendar windows for day/date
Case Compatibility	Fits date-only watch dials and cases	Requires a day-date dial aperture

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Note  the Miyota 8215 does not use a Pellaton winding system; it uses a traditional unidirectional winding rotor system. [1, 2]

• Winding Mechanism: The Miyota 8215 winds in only one direction (counter-clockwise/left rotation of the rotor as viewed from the back).
Pellaton System: The Pellaton winding system is a distinct, patented bi-directional pawl-lever system developed and used primarily by IWC (International Watch Co.), not Citizen/Miyota

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