Cal. 4S27, made from 2003 through 2007, is one of the most complicated automatic movements produced by Seiko. Complications on this modular movement include retrograde day, date by pointer, 24 hour subdial, and independently adjustable hour hand. It was part of the second “wave” of movements in the Seiko 4S family, which itself was derived from the historic Seiko 52 stream of movements. Cal. 4S27 is similar in design to Cal. 4S77, though it lacks the upscale finishing and regulation of that movement. Unlike most 4S movements, Cal. 4S27 has 50 hour power reserve.
Most watches using this movement have the look of a chronograph, with subdials at 6:00 and 9:00 and a power reserve pointer near 3:00. A second crown at 2:00 on the dial adjusts the central 12 hour hand in 1-hour increments, leaving the 24 hour subdial as “home time.” Many examples include a rotating inner bezel with a third crown at 4:00, completing the chronograph look.
- A retrograde pointer at 2:30 shows the day clockwise on a “fan”
- A subdial at 6:00 shows the date using a small pointer
- A subdial at 9:00 shows “home time” using a hand on a 24 hour scale
Cal. 4S27 was used in the Seiko Brightz SAGN Mechanical Retrograde watch series from 2003 through 2007.
- 2003-2007 Seiko Brightz SAGN005
- 2003-2007 Seiko Brightz SAGN007
- 2004-2007 Seiko Brightz SAGN009
- 2004-2007 Seiko Brightz SAGN011
- 2004-2007 Seiko Brightz SAGN013
- 2005-2007 Seiko Brightz SAGN015
Complicated Seiko 4S Movements
After 2000, Seiko had more diverse mechanical movements to choose from. The 4S family was moved upmarket as a base for modules to use in complicated upscale watches. The last 4S movement was retired in 2015.
| Production | Watch | Winding | Jewels | Notes | |
|---|---|---|---|---|---|
| 4S27 | 2003-2007 | SAGN | Automatic | 28 | Retrograde day at 2:00 Date pointer at 6:00 GMT subdial at 9:00 |
| 4S29 | 2003-2007 | SAGN | Manual | 29 | Small seconds at 6:00 Retrograde power at 9:00 |
| 4S36 | 2007-2013 | SAEN SARN | Automatic | 31 | Independent 24 hour hand Retrograde day at 2:00 Date pointer at 6:00 Retrograde power at 9:00 |
| 4S76 | 2004-2010 | GBBT GCBT | Automatic | 31 | Independent 24 hour hand Retrograde day at 2:00 Date pointer at 6:00 Retrograde power at 9:00 |
| 4S77 | 1996? 2000-2005 | GCBG | Automatic | 28 | Retrograde day at 2:00 Date pointer at 6:00 GMT subdial at 9:00 |
| 4S79 | 1998-2015 | GBAY GCAY | Manual | 31 | Small seconds at 6:00 Retrograde power at 9:00 |