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Frederique Constant Index

Most Frederique Constant Index references take a 20 mm watch strap: 11 of 13.

Shop 20 mm

Frederique Constant Index lug width by case size

13 references measured. Updated 2026-10-29.

CaseLug widthReferencesWatch strap attachmentFor example
40 mm20 mm7—FC-303B5B6, FC-303BN5B6B, FC-303C5B4
43 mm20 mm · 23 mm on 25—FC-255S5B6, FC-255V6B4, FC-303S6B6B
not recorded20 mm1—303GR5B6B

References that take a different watch strap

  • FC-303C6B4: 23 mm, not the 20 mm of most 43 mm cases
  • FC-303V6B4: 23 mm, not the 20 mm of most 43 mm cases

Every Frederique Constant Index reference

Other Frederique Constant families

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

All Frederique Constant families → · Why the size changes inside a family →