The verdict, firstCyril Favre

Buy the 104 unless you actually use a second time zone and prefer the 105's matte, black-bezel tool-watch character.

The 104 St Sa I and 105 St Sa share the same 41 mm, 11.9 mm, 20-bar platform, the same day-date function and almost the same automatic movement architecture. The difference is not capability in the abstract; it is what you ask the bezel and case finish to do. The 104 is a polished classic with a 60-minute pilot's bezel. The 105 is a bead-blasted travel instrument with a black hard-coated 12-hour bezel that can keep another time zone visible.

Almost everything else is held constant, which is what makes this a clean decision. Both are 41 mm across, 11.9 mm thick, 73 g without a strap and fitted with 20 mm lugs. Both use sapphire in front with anti-reflective treatment on both sides and a screw-fastened sapphire display back, a screw-down crown, 20 bar of water and pressure resistance to DIN 8310 requirements, low-pressure resistance, and an antimagnetic construction to DIN 8309. Both movements are automatic, with 26 jewels, 28,800 vibrations per hour and stop-seconds. Both bezels are captive and bidirectional, with minute ratcheting and a luminous key mark. Only the scale printed on that bezel — and the finish of the steel around it — actually differs.

Sinn · ~$1,650105 St Sa

Sinn · ~$1,600104 St Sa I

The other case

The 105 is not simply a darker 104 with an extra scale. Its bead-blasted steel, Black Hard Coating on a TEGIMENT base and 12-hour multifunction bezel give the same compact day-date platform a completely different role. If your watch crosses time zones, or if polished steel feels too decorative for the way you dress and travel, the 105 is the more coherent design.

Where it is decided

4 arguments

Design, case finishing and presence

This is a preference, not a ranking, which is why it is a draw. The 104 St Sa I has a polished stainless-steel case and a black pilot's bezel carrying a conventional 60-minute scale: more reflective, more traditional, and closer to an everyday aviation watch than to an instrument. The 105 St Sa has a bead-blasted case and a captive multifunction bezel finished in Black Hard Coating on a TEGIMENT Technology basis, with a 12-hour scale, minute ratcheting and a luminous key mark — a more technical hierarchy of materials and colour. Both carry black dials with luminous hands and indices and the same day-date layout. The consequence is straightforward: the 104 is the better choice if you want one Sinn that moves from casual clothing to a shirt or a jacket without announcing itself as a tool watch; the 105 is the better choice if you want matte finishing, lower shine and an explicitly travel-oriented look. One caution on the hardening: Sinn applies the Black Hard Coating to the bezel on a TEGIMENT basis, so this is a bezel treatment, not a hardened case — nothing here makes the 105 objectively more durable than the 104.

Goes to

Draw

Bead-blasted, black coated bezel
Polished steel, black pilot bezel

Bezel utility and second-time-zone use

Both bezels are captive and bidirectional, both ratchet in minute steps and both carry a luminous key mark. Only the scale differs, and it decides different things. The 104's 60-minute scale is the more immediately intuitive of the two: it times coffee, parking, a meeting, a flight, something on the stove or an exercise interval, and you read it without thinking. The 105's 12-hour scale is designed to indicate a second time zone on a 12-hour basis, which lets a traveller keep home or destination time in view without a fourth hand or a thicker movement. Be clear about what that costs: a 12-hour reading needs your own AM or PM context and a little mental arithmetic, and it is not a substitute for a caller GMT, a flyer GMT or a 24-hour bezel. If you will never set a second zone, the 104's bezel is the more useful one more often — and if you set one weekly, the 105's is. Neither is better in the abstract, so this is a draw.

Goes to

Draw

12-hour scale, second zone
60-minute scale, elapsed time

Movement, capability and daily function

There is no advantage to find here, and inventing one would be dishonest. Both watches are automatic, with 26 jewels, 28,800 vibrations per hour and stop-seconds, and both are built to the antimagnetic requirements of DIN 8309. Both show the day of the week alongside the date. Both use sapphire in front with anti-reflective treatment on both sides and a screw-fastened sapphire display back with internal anti-reflective treatment, both have a screw-down crown, and both are water- and pressure-resistant to 20 bar under DIN 8310 requirements, with low-pressure resistance. Twenty bar is more than enough for normal swimming, travel and active weekend use, provided the crown is screwed down and the seals are maintained. Because the day-date layout is shared too, this pairing is not a contest of complication count — the extra bezel function is the only thing on the table. Sinn does not publish a calibre designation or a power-reserve figure on the current pages for either reference, so we state neither.

Goes to

Draw

26 jewels, 4 Hz, 20 bar
26 jewels, 4 Hz, 20 bar

Ownership proposition and price

On matched entry configurations the two sit remarkably close: the 104 St Sa I is catalogued at €1,490 and the 105 St Sa at €1,550, a gap of about €60 — roughly four percent, which is noise on a watch at this level rather than a reason to choose. That premium is small enough that the 105's bead-blasted case and second-time-zone bezel can justify it easily for the right traveller, and small enough that it should not push anyone away from the 104 who simply wants a day-date pilot watch with an elapsed-time timer. Compare like for like before you commit, though: both models are offered on several straps and bracelets at higher prices, so a bracelet 104 against a leather 105 is not the same comparison. Both use 20 mm lugs, which keeps leather, rubber, textile and bracelet experimentation straightforward and inexpensive on either watch. We make no resale, availability, investment, discount or service-cost claims for either.

Goes to

Draw

€1,550, 20 mm lugs
€1,490, 20 mm lugs

Who should buy which

Sinn 105 St Sa

You regularly track home time, destination time or a second 12-hour time zone while travelling.
You prefer a bead-blasted case and a black hard-coated bezel over polished steel.
You like a more matte, technical and instrument-led visual identity.
You value the TEGIMENT-based bezel treatment and the captive 12-hour multifunction bezel.
The roughly €60 step over the 104 reads as acceptable to you for the bezel function and the case finish.

See the 105 St Sa

Sinn 104 St Sa I

You want a classic, polished pilot-watch look rather than a matte, tool-watch aesthetic.
You use a 60-minute elapsed-time bezel more often than you track another time zone.
You want one watch that moves from office to weekend without looking overly technical.
The black dial, polished case and standard pilot's bezel are exactly why you are buying a Sinn.
It is the lower-priced of the two at matched configurations, and you do not need the second-time-zone function.

See the 104 St Sa I

Your personal verdict

The case dimensions and movement are effectively the same; the real choice is whether you need a 12-hour second-time-zone bezel or a classic 60-minute timer.

Find which one fits you

Explore Sinn pilot and travel watches

The 104 and the 105 each run across several dial and configuration variants, and Sinn's wider pilot and travel range sits directly around them. If the argument above settles the bezel question but not the dial — or if it suggests neither watch is quite the right shape — the answer is usually one of these.

The 104 — dial and configuration variants

The 105 — standard and UTC

If neither is quite the right shape

Frequently asked

What is the difference between the Sinn 104 and Sinn 105?

They share the same platform: a 41 mm steel case, 11.9 mm thick, 73 g without a strap, 20 mm lugs, sapphire front and display back, a screw-down crown, 20 bar of water resistance and a day-date display. Two things differ. The 104 St Sa I has a polished case and a 60-minute pilot's bezel for elapsed timing. The 105 St Sa has a bead-blasted case and a black 12-hour bezel, finished in Black Hard Coating on a TEGIMENT basis, that indicates a second time zone.

Is the Sinn 105 St Sa a true GMT watch?

No. It indicates another time zone by rotating its 12-hour bezel, and that is the whole mechanism. It has no independent GMT hand and no 24-hour display, so the reading is on a 12-hour basis and you supply the morning-or-evening context yourself. If you want a genuine 24-hour hand on the same case, that is the 105 St Sa UTC rather than this reference.

Which Sinn has the more useful bezel: the 104 or the 105?

That depends on you, and neither is universally better. The 104's 60-minute scale is the more intuitive and the more frequently used for most owners: any elapsed-time task reads off it immediately. The 105's 12-hour scale earns its place only if you actually set a second time zone, in which case it does something the 104 cannot. Count how often you time something against how often you need another zone, and the answer follows.

Do the Sinn 104 and 105 use the same movement?

Sinn's current pages state the same figures for both: an automatic movement with 26 jewels, 28,800 vibrations per hour, stop-seconds and an antimagnetic construction to DIN 8309, driving a day-and-date display. No calibre designation or power-reserve figure is published for either reference on those pages, so we do not name one. What matters for a buyer is settled either way: there is no movement advantage on either side of this comparison.

Is the Sinn 105 worth more than the 104?

At matched entry configurations the 105 is catalogued at €1,550 against €1,490 for the 104 — about €60, or four percent. What that buys is specific: a bead-blasted case instead of a polished one, a bezel finished in Black Hard Coating on a TEGIMENT basis, and a 12-hour scale that can hold a second time zone. If those three things matter to you, the step is easy to justify; if they do not, you are paying for a look and a function you will not use. This is a question of personal value only — we make no claims about resale, discounts or availability.