Widths differ across this line. Enter or pick your exact reference to get its width.
19 or 20 mm
Verification: Listed by the maker for ref. 235.10.38.20.13.001, 235.12.38.20.13.001 and 3 more
Attachment: spring bars
38 to 40 mm cases
Official page: Omega
Report an errorIndicative information. Check your watch before buying a strap: whatsmylugwidth.com is not responsible for an incorrect size.
The story · Since 1957
In 1957 Omega built a plain black-dialled watch with a soft iron cage around its movement so that railway staff, engineers and scientists could work beside powerful electric currents without losing time. It sold so poorly that it left the catalogue after six years, and today Omega keeps bringing it back.
1,000 gauss
1,000 gauss: magnetic resistance of the 1957 original, against about 60 for most anti-magnetic watches of the time
Omega launched the Railmaster ref. CK 2914 in 1957 beside the first Speedmaster and the Seamaster 300, as a watch for railway staff and anyone working near electrical fields. A soft iron inner case and a 1 mm thick dial shielded the hand-wound movement up to 1,000 gauss, when most watches managed about 60. Faced with the Rolex Milgauss and the IWC Ingenieur, it sold weakly and production stopped in 1963.
After almost four decades away, the Railmaster name returned in 2003 alongside the first Aqua Terra, in Aqua Terra style cases of 36, 39 and 42 mm with automatic Co-Axial calibres. A 49.2 mm hand-wound XXL with small seconds followed in 2004. Webchronos notes these revivals did not carry the original's high anti-magnetism, and production stopped again in 2012.
For the 60th anniversary Omega reissued all three 1957 watches. With no original drawings left, it digitally scanned a CK 2914 case and rebuilt the Railmaster at the same 38 mm size, now driven by the Master Chronometer calibre 8806 rated to 15,000 gauss, in 3,557 pieces. Phillips writes that the scanned blueprint was a ref. 2914-1.
Alongside the limited edition, Omega added a regular Seamaster Railmaster in a fully brushed 40 mm case with a vertically brushed dial and calibre 8806. It came in black, light grey and a denim blue version and stayed in production until 2024.
In May 2025 Omega relaunched the Railmaster in a 38 mm brushed and polished case shared with the Aqua Terra, in grey with central seconds (calibre 8806) or beige with small seconds (calibre 8804). Both are no-date watches resisting 15,000 gauss, offered on leather or on a redesigned steel bracelet with a comfort adjustment.
Film role: as palaeontologist Dr Henry Loomis in Jurassic World Rebirth (2025) he wears the 2017 Railmaster 60th Anniversary limited edition on a brown leather strap. Bailey, an Omega ambassador, told GQ he picked the 1957 Railmaster for the character and Omega's CEO found him the homage model. At the film's premieres he wore a 2025 38 mm Railmaster.
Series role: as the assassin known as the Jackal in the TV series The Day of the Jackal (2024) he wears a 40 mm Seamaster Railmaster on a black fabric strap. The show's costume designer Natalie Humphries told GQ the Railmaster felt like the perfect expression of the character.
During the Oppenheimer promotion in 2023, and at the SAG-AFTRA Foundation Conversations in Los Angeles on 11 December 2023, he wore his own vintage 36 mm Railmaster ref. 2504.52 on a black leather strap, according to GQ France.
Wore a 2025 38 mm Seamaster Railmaster with grey gradient dial on a black leather strap at the BAFTAs in February 2026, according to WatchPro. Single trade-press source.
Film role: Jonathan Bailey's palaeontologist Dr Henry Loomis wears the Railmaster 60th Anniversary limited edition, swapped from its bracelet to a brown leather strap. Omega tied the choice to the original's purpose as a tool for scientists.
TV role: Eddie Redmayne's Jackal wears a 40 mm Seamaster Railmaster on a black fabric strap in the series The Day of the Jackal.
Phillips sold a 1960 CK2914 made for the Pakistani Air Force for CHF 27,500, against an estimate of CHF 12,000 to 18,000. It mixes the Railmaster case and movement with a Seamaster dial and caseback, is engraved P.A.F., and Phillips says only about 200 were made.
On 10 May 2021 Christie's sold a CK 2914 made on 15 October 1957 and delivered to Singapore for CHF 16,250. A 1958 example with its original 1959 bracelet had made CHF 11,875 at Christie's on 11 May 2009.
The 38 mm relaunch in the Aqua Terra case: grey gradient dial with central seconds (calibre 8806) or beige gradient dial with small seconds (calibre 8804), 150 metres water resistance, display caseback.
Omega lists 19 mm between the lugs and 44.92 mm lug to lug. The three-row bracelet tapers from 19 mm to a 17 mm butterfly clasp with a 2 mm tool-free adjustment; the leather versions (235.12...) close with a foldover clasp.
The 60th Anniversary limited edition of 3,557 pieces: 38 mm case, black 'tropical' dial, calibre 8806.
Omega lists 19 mm between the lugs, 48 mm lug to lug and 12.70 mm thickness, on a steel bracelet with a foldover clasp and comfort setting.
The regular production Seamaster Railmaster: 40 mm fully brushed case, vertically brushed black dial with vintage Super-LumiNova, calibre 8806, 150 metres water resistance. Grey (220.10.40.20.06.001) and denim (220.10.40.20.03.001) versions followed.
Omega lists 20 mm between the lugs and 47 mm lug to lug, on a fully brushed integrated steel bracelet with a butterfly clasp. This is the only Railmaster generation here at 20 mm; the 38 mm models take 19 mm.
Railmaster models in 36, 39 and 42 mm Aqua Terra style cases with automatic Co-Axial calibres, followed in 2004 by the 49.2 mm hand-wound XXL ref. 2806.52.37 with small seconds.
Omega's vintage database groups the CK 2914 and its successor ST 135.004 as one Railmaster family produced in the international collection from 1957 to 1963.
The original: 38 mm steel case with a mu-metal inner case acting as a Faraday cage, broad arrow hands, hand-wound calibres 284, 285 and 286, water resistant to 60 metres. Early examples had a blank caseback; later ones carried the seahorse engraving.
Fratello states the original CK 2914 has a 19 mm lug width, the same as the 2017 reissue; Omega lists it on a leather strap.
Omega Seamaster Railmaster references in our database. Each card says where its width comes from: listed by the maker (linked to the maker's page in the details), two independent sources agree, or listed in our database and not yet verified by us.
Seamaster Railmaster
Lug width: 19 mm
Source: Not yet verified Attachment: Spring barsCase size: 38 mmBlack dialCase material: Steel
Seamaster Railmaster
Lug width: 19 mm
Source: Not yet verified Attachment: Spring barsCase size: 38 mmBlack dialCase material: Steel
Seamaster Railmaster
Lug width: 19 mm
Source: Not yet verified Attachment: Spring barsCase size: 38 mmBlack dialCase material: Steel
Seamaster Railmaster 38mm - Brown on Bracelet
Lug width: 19 mm
Source: Maker Attachment: Spring barsCase size: 38 mmBrown dialCase material: Steel
Seamaster Railmaster 38mm - Brown on Leather Strap
Lug width: 19 mm
Source: Maker Attachment: Spring barsCase size: 38 mmBrown dialCase material: Steel
Seamaster Railmaster 38mm - Grey on Bracelet
Lug width: 19 mm
Source: Maker Attachment: Spring barsCase size: 38 mmGrey dialCase material: Steel
Seamaster Railmaster 38mm - Grey on Leather Strap
Lug width: 19 mm
Source: Maker Attachment: Spring barsCase size: 38 mmGrey dialCase material: Steel
Seamaster Railmaster Co-Axial 40mm Black
Lug width: 20 mm
Source: Maker Attachment: Spring barsCase size: 40 mmBlack dialCase material: Steel
No reference matches.
Omega Seamaster Railmaster references use 19 mm or 20 mm depending on the reference and case size, so check yours in the list below. The most common is 19 mm (7 of 8 references with a known width). The Omega Seamaster Railmaster ref. 235.10.38.20.13.001, 235.12.38.20.13.001 and 2 more take 19 mm (listed by the maker). The Omega Seamaster Railmaster ref. 220.10.40.20.01.001 takes 20 mm (listed by the maker).
No. 2 different lug widths appear across the line, often by case size or generation. Check the reference engraved on the case back or between the lugs.
It depends on the generation. The 38 mm models, from the 60th Anniversary edition to the current grey 235.10.38.20.06.001, take 19 mm. The 40 mm Seamaster Railmaster takes 20 mm.
Fratello reports that the 2017 reissue keeps the 19 mm lug width of the original CK 2914, so both take 19 mm straps.
The three-row bracelet tapers from 19 mm at the end links to a 17 mm butterfly clasp with push buttons, and the clasp has a tool-free 2 mm comfort adjustment. The brown Novonappa leather strap tapers to 16 mm at a steel folding clasp.
Omega gives 38 mm across, 44.92 mm lug to lug and 12.36 mm thick, the same case as the 38 mm Aqua Terra.
The gap between the two lugs that hold the strap, in millimetres. A new strap must match it exactly: 20 mm lugs take a 20 mm strap.
Most watches use spring bars, so any strap of the right width fits. Many smartwatches use their own band system instead, such as Apple Watch bands or Garmin QuickFit.