6R15 is one of a family of modern automatic upper-midrange watch movements from Seiko. The 6R15 is also sold as the NE15A. A “high beat” derivative with a chronograph module is also available, called the Seiko 8R28.
The 6R15 family was introduced in 2006 as a higher-spec derivative of the familiar Seiko 7S26. It was intended to replace the expensive “high beat” King Seiko-derived 4S15 in mainstream watches, allowing that family to be used exclusively in more expensive models.
The 6R is an automatic movement which adds hacking and hand winding to the existing 7S26 base. This is the main difference between the movements. The winding works now include two separate pinions on the bottom plate to add hand winding. It also features a hacking mechanism and pinned balance spring for adjustability. Thanks to a Spron 510 mainspring, the 6R15 boasts 50 hour power reserve, and the faster-beating 6R2x series has a 45 hour power reserve.
The 6R20 differs from the base 6R15 in many ways. It beats at 28,800 vph and features a power reserve indicator and both day and date in a window. The derived 6R21 and 6R24 also beat at 28,800 and have power reserve indicators but add day and date on subdials (sweep for the 6R21 and retrograde for the 6R24).
As of 2018, the 6R15 is used in the Seiko Prospex SBD series of watches, which start at $600, as well as the higher-end Prospex and Presage SPB and Seiko Core SDG.
| Movement | Beat | Winding | Hands | Date | Subdial | Jewels | Power reserve |
|---|---|---|---|---|---|---|---|
| 6R15 | 21,600 | Automatic | Hour, minute, seconds | Date window | None | 23 | 50 hours |
| 6R20 | 28,800 | Automatic | Hour, minute, seconds | Day and date window | Power reserve indicator | 29 | 45 hours |
| 6R21 | Automatic | Hour, minute, seconds | Sweep day and date subdials | Power reserve indicator | |||
| 6R24 | Automatic | Hour, minute, seconds | Retrograde day and date subdials | Power reserve indicator | 31 | ||
| 6R27 | Automatic | Hour, minute | Sweep date subdial | Sweep date, retrograde power reserve indicator | 29 |
The following movements were all based on the Seiko 7S26 movement.
The Seiko 6R15 is commonly found in upper-midrange models, but was also used in Seiko's 100th anniversary “Laurel” tribute, SARX011. 6R27 is very rare, only used in the 100th anniversary “Laurel” tribute, SARW005.
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