Sinn 104

Cardinal Sinn! Exploring the Sinn 104 in detail - Part 1

8 min read
Don Russell



Don Russell



The 104 is one of Sinn's best sellers, but all too often gets overlooked by many adventurers, explorers and mountaineers, not to mention the more serious outdoor enthusiasts.

The Sinn 104 falls into the pilot watch category, but as with most things, it's not quite as simple as that. As my own escapades are generally conducted on land or underwater, my choice of timepiece is usually of the hardcore diver type and, as such, I too have overlooked the Sinn 104.

Sinn 104

Sinn 104 on test being worn on a ZULUDIVER Military Nylon - Credit WatchGecko

Other than the rotating bezel, the 104 presents as a 'pilot watch' with its incredible clarity and no-nonsense dial. The main text is pleasantly sparse, comprising of just 'Sinn' and 'Automatik', with 'Made in Germany' squirrelled away either side of the 6 o'clock position, but this is only a taster of the 'everything you need and nothing you don't' character of the 104. At the risk of stating the obvious, Sinn is German, and although this is evident on all Sinn 'instrument' watches, it's blatantly obvious with the 104. But what exactly do I mean by that? When you pick up a Sinn watch, the first thing that hits you is that there's nothing on it that doesn't need to be there, no bells, no whistles. Looking a little deeper, it becomes apparent that Sinn's continual pursuit of functionality is what makes them so popular among professionals.

Sinn 104 dial

Sinn104 white dial macro - Credit WatchGecko

It all started with a 'ping' and a WhatsApp image of a boxed Sinn 104 from my good friend Richard at WatchGecko, asking if I'd like to review it. I've been a follower of Sinn for as long as I can remember but never actually bought one, although I've been extremely close with the U1 on more than one occasion. During my many periodic trawls through the Sinn website I have continually scrolled past the 104 with little interest, but after spending some time with it I realise that in my impatient dash to get to Sinn's hardcore collection I have not only done the 104 a serious injustice, but also myself.

I sat at my desk and unboxed the 104; everything about it screamed Sinn and I instantly warmed to it, even though it wasn't something that I'd normally consider. My first job was to adjust the bracelet, and being an engineer, boy, was I in for a treat! Cap heads! I knew that Sinn used cap heads on their bracelets, or to use the correct term 'socket head cap screws' but I'd never actually worked on one. The pin itself has a shouldered, socket drive head and a machined diameter, with a tapped hole to accept the cap head screw from the other side. The tolerance on the length is such, that when it's fully tightened it still turns freely but with virtually no end float. Supplied in the box are two Allen keys and a small bottle of thread lock to ensure that everything stays where it should, no matter what you get up to! If you gave a bracelet to an engineer and said “Here! Fasten this together.” that's exactly how it would be done; this 'how it should be' trend continues throughout the 104, as it does throughout all of Sinn's professional series. Unless you're an engineer, things like this often go completely unnoticed.

The specification of the Sin 104

I'll just cover the basic specification for the benefit of any potential buyers. First up is the 104's power supply, a Sellita SW220-1 premium grade movement sporting a Sinn custom rotor. The SW220-1 being based on the ETA 2836-2 and this, in turn, is an ETA 2824-2 (SW200-1) with an additional day complication. It's a 26 jewel, self-winding and hacking Swiss movement with a day/date complication. It has a power reserve of around 38-40 hours, a beat rate of 28,800vph (4Hz) and is also anti-magnetic in accordance with DIN 8309. The case diameter is 41mm and the case material is 316L stainless steel. The lug-to-lug dimension is 48,5mm and the lug width is 20mm. The thickness is 11,9mm and the weight of the watch head is 73g.

Sinn 104 white dial

Sinn 104 - Credit WatchGecko

The front crystal is sapphire with AR coating on both sides and, unusually, the exhibition caseback crystal is also sapphire with an AR coating on the underside only. The rotating bezel is semi-coin edge with interruptions every 30 degrees. It's of the captive type and is retained in position by 3 machine screws that are equally spaced at 120 degrees, the first one starting at the 2 o'clock position. The bezel is bi-directional, of a sprung detent design and is countdown graduated in complete minutes with a luminous triangle (key mark) at the 0/60 position. The bezel insert is of the anodised aluminium type with a satin finish that's only just short of gloss. The water resistance is 200m (20 bar) and is compliant to DIN 8310. The crown and caseback are both screw down as one would expect, and when the crown is pulled out, its rigidity is beyond impressive. With Sinn, it's all about what you don't see! The functions are hours, minutes, seconds, day and date. In addition, the watch is also protected against a sudden reduction in atmospheric pressure such as that experienced during the emergency decompression of an aircraft fuselage. 

The dial & handset

This particular specimen has a printed, white dial with all markings in black. First impressions are that it's quite basic, but it's a Sinn and there's much more to it. The heavily lumed syringe hour & minute hands not only compliment the watch perfectly, but also ensure incredibly accurate timing at a glance. The arrow style seconds hand is also lumed and equally competent at its job. Overall luminosity is good for this type of watch, and the time is readable well into the night; it would be unfair to compare the lume to something like the Squale 101 Atmos or the HELM Vanuatu. The day/date at the 3 o'clock position is clear and perfectly centred; the day can be set in German as well as English which is also a nice touch. The day and date wheels are white with black text, keeping everything, well, Sinn. The day & date change simultaneously at one minute to midnight and are so quick that you can't actually see them! It's nothing in itself, but it'll certainly bring a smile to your face!    

Sinn 104 macro

Sinn 104 - Credit WatchGecko

The bezel

I feel that the bezel is worthy of an extended description from that in the specification. It is bi-directional and is of the countdown type, meaning that '55' is at the '5 minute' position, '50' is at the '10 minute' position and so on; it has a luminous triangle (key mark) at the 0/60 position. This type of countdown bezel doesn't seem to be anywhere near as popular as the usual time elapsed bezel on a diver's watch, but in actual fact it's far, far more useful. The bezel on the 104 has 60 clicks as opposed to the 120 clicks that now seems to be the industry norm; however, there's more to this than meets the eye and I'll come back to that later. The three retaining screws completely eliminate the possibility of detaching the bezel accidentally. Operating the bezel is an absolute joy, and to say that it's just exceptional is almost bordering on an insult! Every single detent aligns perfectly with the minute track and there is absolutely no movement whatsoever in either direction. It is firm, well engineered and inspires confidence during operation.

Timing with the bezel

I said earlier that there was a little more to the 60 click bezel and that I'd explain further. Some reviewers have said that because it's a 60 click bezel, it often can't be aligned exactly with the minute hand for accurate timing. In reality, a 60 click countdown bezel offers timing to the second and almost at a glance! The syringe minute hand is so precise that it's an absolute doddle to set the watch accurately, so that the minute hand aligns exactly with the minute track marker when the seconds hand is hacked at the 12 o'clock position; when the seconds hand is at the 12 o'clock position, the bezel markings will align exactly with the minute hand. Once the countdown is complete, the minute hand will align with the luminous key mark on the bezel exactly at the time when the seconds hand reaches the 12 o'clock position. As the accuracy of a measuring instrument is generally regarded as it's smallest graduation, the countdown can been measured to a quarter of a second with incredible clarity!

Sinn 104 black dial

Sinn 104 alternative black dial - Credit WatchGecko

The case

Other than the underside, the case is completely polished. Yes, I know, it'll no doubt pick up a few scratches, but it's easily refinished. The shape of the case is such that only Sinn would get away with it! It is so function orientated with its angles and chamfers that, coupled with the same 'everything you need and nothing you don't' trend on the rest of the watch, produces a beauty that can only be Sinn. The case is 316L stainless steel and is not treated in any way.  


The Sellita SW200 series is not only a joy to work on but an extremely consistent performer under all conditions. It came as no surprise whatsoever that this premium grade movement performed impeccably during the seven days that I had the pleasure of it on my wrist. The accuracy of this particular watch over those seven days was +14 seconds! Whenever the 104 was not being worn, it was placed in the dial-up position. That's an average accuracy of around +2 seconds a day, or 99.99768524%! This is Rolex territory, but like most things, it's nowhere near as simple as that! Of course, not every 104 is likely to perform to this standard, and I accept that I've been quite fortunate; however, it's a random watch straight out of the box, and by all accounts this is by far from unusual. I've heard it said that the Sellita isn't quite as good as the ETA from which it's cloned. In my collection I have watches with both the Sellita SW200-1 and the ETA 2824-2 but would find it extremely difficult to say one way or the other. Both movements have always performed faultlessly and keep excellent time. I've worked on both without any cause for complaint with either movement.

As this is a major review of the Sinn 104 we have taken the decision to split it into two parts. Click here to jump straight to part 2.  See our Sinn collection in detail here. 



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Don Russell

About the Author: Don Russell

The timepiece of an adventurer serves not only as a trusted companion, but also as a portal to their inner self. My interest in watches goes back more than half a century; my reliance and passion more than half of that time. My hope is that I may inspire others to use their timepiece on their own adventures so that they may share a passion that has enriched my own life and given me so much enjoyment.

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