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Grand Seiko Mechanical

Most Grand Seiko Mechanical references take a 19 mm watch strap: 26 of 38.

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Grand Seiko Mechanical lug width by case size

38 references measured. Updated 2026-10-29.

CaseLug widthReferencesWatch strap attachmentFor example
37 mm19 mm · 20 mm on 12—SBGR253
38 mm19 mm4—SBGH219, SBGH220, SBGH222
39 mm19 mm4—SBGM227, SBGR255, SBGR257
40 mm19 mm · 20 mm on 3 · 22 mm on 2 · 18 mm on 122—SBGH213, SBGH243, SBGH245
41 mm20 mm1—SBGR305
42 mm21 mm2—SBGR307, SBGR309
47 mm20 mm · 23 mm on 12—SBGH257
not recorded19 mm1—SBGJ217

References that take a different watch strap

  • SBGR251: 20 mm, not the 19 mm of most 37 mm cases
  • SBGH201: 20 mm, not the 19 mm of most 40 mm cases
  • SBGH205: 20 mm, not the 19 mm of most 40 mm cases
  • SBGJ001: 20 mm, not the 19 mm of most 40 mm cases
  • SBGJ210: 18 mm, not the 19 mm of most 40 mm cases
  • SLGH002: 22 mm, not the 19 mm of most 40 mm cases
  • SLGH025: 22 mm, not the 19 mm of most 40 mm cases
  • SBGH255: 23 mm, not the 20 mm of most 47 mm cases

Questions about the Grand Seiko Mechanical

Can two Grand Seiko Mechanical watches with a 40 mm case take different watch straps?

Yes. Of the 22 Grand Seiko Mechanical references with a 40 mm case, 16 take 19 mm, 3 take 20 mm and 2 take 22 mm. The reference number decides, not the case size alone.

Every Grand Seiko Mechanical reference

Other Grand Seiko families

Inside each one the lug width often changes: it is the reference that decides.

All Grand Seiko families → · Why the size changes inside a family →