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Seiko 8L35

High confidence

The Marinemaster and high-end Prospex caliber. Related to the Grand Seiko 9S by architecture and assembly facility, but NOT regulated to Grand Seiko's standard and not finished to it — a distinction that listings routinely collapse into 'the Grand Seiko movement'. It is a strong movement described accurately; it does not need the overclaim.

Specifications

Movement manufacturer
Seiko
Production
2000–present
Frequency
28,800 vph (4 Hz)
Jewels
26
Power reserve
50 hours
Winding
automatic
Complications
Date · Hacking seconds · Hand-winding

Architecture

Automatic caliber sharing its architecture with the Grand Seiko 9S series, supplied undecorated and unadjusted to Grand Seiko's standard.

Authentication notes

  • MovementProbable

    'Grand Seiko movement' is an overstatement worth correcting

    The 8L35 is architecturally related to the 9S series and is assembled at the same facility, but it is neither decorated nor adjusted to Grand Seiko's accuracy standard. A listing describing an MM300 as containing a Grand Seiko movement is overstating the specification. This is a description accuracy point rather than an authenticity one.

Related calibers

  • Related caliber

    Seiko 9S65

    Shares architecture; differs in finishing and in regulation standard.

References using this caliber

Provenance of this record

Sources & Evidence

Primary sourceManufacturer documentation

Seiko — Prospex, Presage, 5 Sports and Astron product documentation

Seiko Watch Corporation

Accessed
2026-08-18

Cited for

This referenceHigh confidence
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Last verified: Not yet reviewed