§ 01 — Craftsmanship

Le Sentier · 46°36′N 6°14′E

CalibreSR-24

4 Hz · 72 h · 228 components

Designed, finished and assembled under one roof in Le Sentier. An automatic GMT whose local hour jumps independently, so crossing a time zone never stops the watch.

Fig. 01 — Free-sprung balance, 4 HzBeats since you arrived

The sapphire caseback of the Traverse GMT showing calibre SR-24, its rotor, bridges, blued screws and jewels.

01 · Caseback

Look inside.

A sapphire caseback, ringed in Glacier Steel and engraved by hand. Scroll, and the camera goes through it.

02 · Rotor

Openworked tungsten.

Heavy enough to wind the mainspring on the smallest gesture, open enough to show the bridges beneath it.

03 · Bridges

Côtes de Genève.

Rhodium-plated bridges, striped and bevelled by hand. Blued screws, red jewels in polished chatons.

04 · Balance

Eight beats a second.

The free-sprung balance with its silicon hairspring: 28,800 vibrations an hour, −2/+2 seconds a day.

Through the sapphire01 / 04

§ 02 — Exploded view

Seven layers. 12.1 millimetres.

The Traverse comes apart along its axis, from the crystal you look through to the sapphire you look into.

Scroll to take it apart

01Sapphire crystal
Flat sapphire, 9 on the Mohs scale, anti-reflective on the inner face only.
02Ceramic bezel
A zirconium-oxide insert on a 48-click ring, its numerals filled with platinum.
03Hands
Faceted sword hands with lume channels, and a red arrow that keeps home time.
04Obsidian dial
Twelve coats of black lacquer under applied white-gold batons and the peak.
05Glacier Steel case
40.0 mm of vacuum-remelted 316L, brushed on top, polished on every bevel.
06Calibre SR-24
228 components, 31 jewels and 72 hours of reserve, beating at 4 Hz.
07Sapphire caseback
A second crystal, so the movement reads as clearly as the time.

§ 03

The calibre in seven numbers

Calibre SR-24 · Automatic GMT

Numbers, not adjectives.

Every value below is measured on a cased watch, not on a loose movement. Where a figure varies from piece to piece, we publish the limit it is not allowed to cross.

01Frequency: 28,800vph; 4 Hz. The balance swings eight times a second.
02Jewels: 31rubies; Synthetic ruby at every pivot that would otherwise wear.
03Power reserve: 72h; Take it off on Friday evening. It is still running on Monday.
04Components: 228parts; Each finished before assembly, including the ones no one will see.
05Diameter: 30.4mm; Sized to the 40 mm case, so the rotor sweeps the whole caseback.
06Height: 5.9mm; Thin enough for a 12.1 mm case sealed to 100 metres.
07Accuracy: −2 / +2s / day; Measured cased, after the Glacier Protocol, not before it.

§ 04

Materials

Ceramic · Steel · Sapphire · Lacquer · Hand

Four materials. One pair of hands.

Each was chosen for what it does after twenty years on a wrist, not for how it looks on the first day.

Material 01

Ceramic

ZrO₂ · 1,450 °C · 1,250 HV

Zirconium oxide, pressed, sintered and engraved. The numerals are filled with platinum and polished flush. The colour is in the material itself, so twenty summers of sun cannot fade it.

Four engraved ceramic bezel inserts laid out on a black finishing tray under a strip light — Fig. 4.1 — Engraved inserts on the finishing tray

Fig. 4.2 — The night half, from 18 to 6

Material: Zirconium oxide
Sintering: 1,450 °C
Hardness: 1,250 HV
Bezel: 24 h · 48 clicks

A row of polished steel watch cases lined up in front of a polishing wheel — Fig. 4.3 — Cases waiting for the polishing wheel

Material 02

Glacier Steel

316L · Vacuum-arc remelted

Steel remelted under vacuum to drive out the inclusions that pit a case over time. Every lug top is brushed in one direction; every bevel is polished by hand, at 45°.

Case: 40.0 × 12.1 mm
Lug to lug: 47.6 mm
Lug width: 20 mm
Water resistance: 100 m

Fig. 4.4 — Flank, bevel and screw-down crown

Fig. 4.5 — Light across the flat sapphire

Material 03

Sapphire

Al₂O₃ · Mohs 9 · Inner AR

Synthetic corundum, grown as a single crystal and cut flat: nine on the Mohs scale, one step below diamond. The anti-reflective coating sits on the inner face, where nothing can scratch it into a haze.

Crystals: 2
Front: Flat, 3.0 mm
Back: Exhibition

Grazing light along the polished edge of the sapphire crystal above the black dial — Fig. 4.6 — The crystal's edge, grazing light

The faceted white-gold peak index at twelve above the SERAC name on the black lacquer dial — Fig. 4.7 — The peak at twelve

Material 04

Obsidian lacquer

12 coats · 3 days · White gold

Twelve coats of black lacquer, each fired and polished by hand before the next is laid. Three days for one dial. The peak at twelve is applied white gold, one half mirror-polished, the other filled with lume.

Fig. 4.8 — Light travelling over twelve coats

Coats: 12, fired between each
Indices: Applied white gold
Lume: Every hour, and the peak

Material 05

The hand

1 watchmaker · 1 movement · 5 days

Everything above ends on one bench. The 228 components of each SR-24 are assembled, regulated and cased by the same pair of hands, from first screw to final seal.

Their initials are engraved under the rotor, where only a watchmaker will read them.

A watchmaker's gloved hands holding tweezers over an open movement under the bench lamp — Fig. 4.9 — Assembly, Le Sentier

§ 05

The Glacier Protocol

Tested cased · Le Sentier bench

The Glacier Protocol

Before a Traverse leaves Le Sentier it spends fifteen days cased and running on the bench, turned through six positions and three temperatures, measured every twenty-four hours. If it drifts beyond two seconds a day, either way, it goes back to its watchmaker.

Days: 15; Cased, running, on the bench
Positions: 6; Two days in each
Temperatures: 3; 8 °C · 23 °C · 38 °C
Seconds a day: −2 / +2; Or it goes back to the bench

Fig. 5.1 — A typical record. Every Traverse is delivered with its own.

Outer ring15 days, read clockwise from the top

GlyphsDU dial up · DD dial down · CU crown up · CD crown down · CL crown left · CR crown right

Stepped ringBench temperature, 8 · 23 · 38 °C

Inner bandDaily rate, −2 to +2 s · mean +0.2 s

§ 06

Finishing

Seen through the sapphire caseback

Finished where no one looks.

Most of the SR-24 sits under its rotor, against the wrist. It is finished as if it were on display, because through the caseback, it is.

Fig. 6.1 — The openworked rotor winding the calibre

Calibre SR-24 in macro: the balance, blued screws, striped bridges and the grained main plate

The sapphire caseback with the rotor of calibre SR-24 behind it

Fig. 6.2 — Loupe

×1.0 · Balance side

Parallel waves cut across the bridges with a turning wheel, one pass per stripe. They catch the light, and hold dust away from the train.
Overlapping circles grained into the main plate with a turning peg, about 1,400 of them, each placed by hand.
Every bridge edge is bevelled at 45° and polished with gentian wood and diamond paste. Inward angles cannot be cut by machine.
Polished steel heated to 290 °C until it turns blue. The colour is an oxide layer, and it resists corrosion.
Tungsten, for weight at the rim. Cut open, so the calibre stays visible while the rotor winds it.

§ 07

Your Traverse

Configurator · Private inquiry

Choose the bezel. Keep the calibre.

Four bezels, three dials, three straps. Every combination carries calibre SR-24 and leaves Le Sentier with its own Glacier Protocol record.

Open the configuratorPrivate inquiry