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The Sinn 105 St Sa has been part of the collection of the traditional Frankfurt manufacturer since last fall. The classic tool watch with the reduced design promises the highest functionality – whether it deserves the title ‘special watch’? My very first Sinn watch in a review…

Sinn 105 St Sa
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Sinn in the Uhrenlounge

For this review, the Sinn 105 St Sa was kindly provided to me by the online portal The Uhrenlounge of the Aika Jewelers from Dresden is specialized in online sales of watches of well-known manufacturers like Oris, Tissot, Hamilton and Sinn. At the end of this review you will find links to the shop, where you can find more Sinn watches as well as many other timepieces! If you have any questions about watches, the competent customer service of Uhrenlounge is at your disposal.

My first Sinn watch!

Sinn 105 St Sa
Photo © 2021 by WATCHDAVID® – All rights reserved

Premiere for Sinn at WATCHDAVID®! It doesn’t happen too often anymore, but I still discover new brands. Sure, Sinn has been a household name for me for a long time. The hype around the special watches from Frankfurt might have escaped few people. Nevertheless, the Sinn 105 St Sa is for me the first watch of the brand, which I may test. So now you are with me as I get to know not only a new wristwatch, but also a new brand.

The world of Sinn is dominated by functional tool watches – or rather special watches, as the manufacturer itself calls them. The pilot watches, diving watches and instrumental chronographs are trimmed to offer their wearer the perfect utility. Best readability, precise accuracy and a design reduced to the essentials are the outstanding characteristics of the premium watches from Frankfurt. Does this explain the great popularity among customers?

The Sinn 105 St Sa was introduced in the fall of 2020 as the base model of the new 105 model series. The timepiece with the reference number 105.010 seems to be the right entry-level model to get to know the brand – the perfect watch for testing and watch photography.

Unboxing: Aviator? Diver? Both?!

Sinn 105 St Sa
Photo © 2021 by WATCHDAVID® – All rights reserved

The black packaging bears the lettering of the German manufacturer. I open it and first look at the “package insert”. A detailed instruction manual with explanations of the design in German and English and (especially important) the warranty card from Uhrenlounge. The actual box with a fancy black leatherette cover is underneath. Sitting on a clasp is the still-packaged Sinn 105 St Sa. sent me the tool watch with the functional rubber strap including a folding clasp. Optionally, there is also a classic stainless steel bracelet.

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The design of the Sinn 105 St Sa is basically based on the 104 Pilot’s Watch. At least, I can see clear parallels here. Unlike the latter, however, the 105 St Sa cannot be clearly identified as a pilot’s or diver’s watch. While the straightforward and reduced dial is without any totalizers and strongly reminds of a diver’s watch, the bi-directional rotating bezel is clearly the identifying feature of an aviator. Category: tool watch, right?!

The workmanship is strikingly good. All surfaces of the case, bezel and bracelet feel very high-quality and are a foretaste of Sinn’s premium claim.

The Sinn 105 St Sa on the wrist

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Hands on! After adjusting the rubber strap with the folding clasp using the included tool, I put the watch on. With a diameter of 41 millimeters, the case has a medium size that fits any wrist. ‘Compact’ would be the appropriate term. The case height is impressively sporty. It measures just 11.90 millimeters. Just a reminder: inside this timepiece works an automatic caliber!

Visually, the Sinn 105 St Sa is an unusual representative of the Frankfurt manufacturer. I would describe the design as perhaps the most approachable of the brand, which brings certain benefits. The reduced aesthetics with stainless steel, lots of black and orange second hand make the Sinn 105 St Sa practically timeless. This design will not go out of fashion! Another advantage: despite its sportiness and functionality, the wristwatch is, in my opinion, perfectly suited for everyday wear on the job – a real plus!

The case: good quality and groundbreaking technologies

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The simple, circular case is made of robust and durable stainless steel, which is bead-blasted and features primarily satin-finished surfaces. Without any transitions, it merges into the massive lugs, whose spacing is 20 millimeters. The workmanship of the stainless steel is extremely successful. Sinn’s 105 St Sa shows particular attention to detail on its back. The six-screw case back is a real eye-catcher! In the center, Sinn has installed a generously sized, circular viewing window through which you can admire the automatic caliber.

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The specifications of the model are engraved on the edge, as well as the serial number and water resistance. Sinn specifies the water resistance at 20 bar. That makes a maximum diving depth of 200 meters; quite a remarkable value. This gives the Sinn 105 St Sa real diving qualities and makes the tool watch particularly flexible. The watch glass is made of resistant sapphire, which is to be expected for a timepiece in the low four-digit price segment.

I find the black bezel quite interesting. Here, a well-known and special Sinn technology is used: The rotating bezel is made of stainless steel, whose hardness has been increased with the so-called TEGIMENT technology (tegimentum, Latin for protective coating). The increased degree of hardness protects the bezel from scratches much more effectively. An hour and a minute index are printed on the surface. The bezel can be rotated on both sides, which allows you to use it flexibly. Only 60 clicks engage cleanly and without play.

The movement of the Sinn 105 St Sa

Sinn 105 St Sa
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Inside the Sinn 105 St Sa works a Swiss automatic caliber. Once fully wound, the Sellita SW 220-1 offers a power reserve of a sufficient 38 hours. Many components of the movement are anti-magnetic. This guarantees a good accuracy. In my opinion, a visual eye-catcher is definitely the gold-colored rotor with black Sinn lettering. Winding it up via the screw-down crown is easy. For everyday use, it is flanked by a crown protector.

Pure minimalism: the dial of the Sinn 105 St Sa

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The highlight of the black and minimalist dial is the date display. Usually found at 3 o’clock, Sinn has positioned it above 6 o’clock on the 105 St Sa. This gives the dial a strict and structuring symmetry that is unparalleled. Above the date window, the day of the week is read in vertical letters – I really like this design solution!

Sinn 105 St Sa
Photo © 2021 by WATCHDAVID® – All rights reserved

The only real color accent is found on the second hand, whose orange tone is very dynamic. A positive side effect: The readability of the time is improved. And that is already above average. Apart from the pill-shaped hour indices, you won’t find any other markings or subdials with additional information. So, the look of the black dial is defined solely by the design of the white hour markers. This is minimalism in perfection. In the dark, white luminous material makes the dial shine.

Sporty: the rubber strap

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The rubber strap with Sinn lettering is exactly the right choice if you want to make perfect use of the functionality of the Sinn 105 St Sa. Diving, sports and other adventures are best enjoyed with a bracelet that you don’t have to worry about its integrity. So in this case, I recommend the rubber version to you. For the more upscale occasions, the stainless steel alternative is suitable.

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Unusual for the rubber strap, but useful, is the stainless steel folding clasp. Before wearing it, you first have to adjust the bracelet to the right length. However, then it guarantees unsurpassed hold and comfort.

My conclusion about the Sinn 105 St Sa

Sinn 105 St Sa
Photo © 2021 by WATCHDAVID® – All rights reserved

You could probably already guess it from the watch photography and the review so far: my first model from Sinn has convinced me all around. The Sinn 105 St Sa is the perfect watch to enter the world of Sinn. With a minimalist yet very accessible design, this timepiece is suitable for anyone who wants to enjoy a true tool watch. As a tool watch, the Sinn 105 St Sa does not commit itself and can thus be used as a pilot’s watch as well as a diver’s watch – not to mention its qualities as a daily rocker.

On the craftsmanship side, I was particularly fascinated by the TEGIMENT technology. Material selection and build quality are on par with a premium watch.

In the Uhrenlounge shop, the Sinn 105 St Sa costs 1.350 euros with a rubber strap as of June 2021. The warranty is 2 years. All other model variants might also be interesting for you. The watch is also available in white and under the name UTC also as a GMT watch.

My final thanks go once again to Uhrenlounge, who provided me with the model for this review!

Sinn 105 St Sa
Photo © 2021 by WATCHDAVID® – All rights reserved

More about Sinn and the 105 St Sa

Here you can find the watch in the shop of Uhrenlounge

Homepage of Sinn

Best Men’s Watches 2021

Technical Details

NameSinn 105 St Sa

Reference number105.010


Categorytool watch

Price from1.350,- Euro

Warranty2 years

Case Material316L stainless steel

Diameter41.00 mm

High11.90 mm

Watch GlassSapphire Crystal

Watch TypeAutomatic

Waterproof20 bar (200 m / 660 ft)

Movement NameSellita SW 200-1

Power Reserve38 hours

Functionsdate / day date / hour / Minute / second



Special Featuresindices filled with luminous material


Bracelet Colorblack

Bracelet Materialrubber

Clasp316L stainless steel / folding clasp

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