Lug

The British Horological Institute, a professional body rather than a standards authority, defines the term in the glossary of its Practical Clock and Watch Servicing Distance Learning Course Technician Grade: lugs are "Projections on wrist watch cases supporting the strap or bracelet." They belong to the case and not to the band, and they exist only because a wristwatch has to be fastened to a wrist.

The measurement that matters to a wearer is the distance between a facing pair, because a strap or bracelet has to be exactly that wide to fit. Manufacturers publish it in millimetres. Omega's own specification for the Speedmaster Moonwatch Professional 42 mm, reference 310.30.42.50.01.002, gives "Between lugs: 20 mm" and, separately, "Lug-to-lug: 47.50 mm". The page gives the two figures without saying what either governs; on this Codex's reading the first is the fitting width a band must match and the second is the overall length of the case across its lugs. They are two different measurements and are easily confused.

The fitting itself is normed in Switzerland, though the norm's text has not been read here. The Federation of the Swiss Watch Industry's list of available NIHS standards, valid from April 2026, includes NIHS 60-81, Timekeeping instruments – Wristwatches – Dimensions of bracelet-to-case fastening elements (1998), and NIHS 60-85, Timekeeping instruments – Wristwatch-cases – Fixing dimensions of non-spring-bar types (2001). Neither text has been read here; their titles establish that the lug fitting is a normed dimension and that not every fitting uses a spring bar.