Seiko 4S15

	Brand:	Seiko
	Family:	Seiko 4S Family
	Height:	4.17 mm
	Jewels:	25
	Reserve:	40 hours
	Frequency:	28,800 A/h
	Winding:	Automatic, Bi-Directional Automatic Winding
	Diameter:	25.60 mm (11.5 ligne)
	Complications:	Date, Hacking Seconds, Hand Winding, Quick Date Correction
	Hands:	Central Hour Hand, Central Minute Hand, Central Seconds Hand, Date Window at 3:00

Distinguishing Technical Characteristics
Clockwise Balance Cock Screw Regulator Balance Balance at 4:30 Barrel at 12:00
Production: 1995 – 2006
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

Cal. 4S15 is an automatic movement with date developed by Seiko in the early 1990s. It was based on the Seiko 52 stream of movements, which had been retired in 1976, and was responsible for Seiko’s resurgence as a maker of high-end watches. Cal. 4S15 was used in many popular watches, including the SUS military watch, Alpinist expedition watch, 200 meter diver scuba, and the 2000 King Seiko reissue.

Cal. 4S15 is identical in design to Cal. 4S25 and the high-spec Cal. 4S35. The only differences are in finishing and regulation, with Cal. 4S15 and 4S25 delivering -15/+25 seconds per day compared to -10/+15 seconds for Cal. 4S35.

Cal. 4S15 was used in a variety of Seiko models, including Brightz, Alpinist, SUS military, the Titanium Scuba Diver’s, and the famous Historical Collection King Seiko reissue.

• 1996-1997 Seiko SUS SCFF
• 1996 Seiko Laurel LHAM600 (blue dial)
• 1996 Seiko Laurel LHAM601 (white dial)
• 1998-1999 Seiko Titanium Scuba Diver’s SCVF001
• 1998-1999 Seiko Titanium Scuba Diver’s SCVF003
• 1998-2001 Seiko Alpinist SCVF005
• 1998-2001 Seiko Alpinist SCVF007
• 1998 Seiko Alpinist SCVF009
• 2000 Seiko Historical Collection King Seiko reissue SCVN001
• 2006 Seiko SAGN001 (Limited Edition of 500 in Brightz titanium)

Early Seiko 4S Movements

From the 1992 introduction of the Seiko 4S family through the early 2000s, Seiko used the 4S line as a high-end movement for diverse watches, including the SUS military, Alpinist, and Titanium diver. Most of these models were retired shortly after introduction, and the series of simple 4S movements was phased out by 2003.