The black-dial Sinn 903 St II is a 41 mm automatic chronograph with a rotating logarithmic slide-rule bezel, a column-wheel movement and 20 bar water resistance. Its headline update is practical: the bezel now turns from its outside edge rather than through a crown at 10 o’clock. Sinn’s November 2025 price list puts it at €3,350 on leather or silicone and €3,650 on a solid bracelet, including tax. Whether it is the better choice than a Breitling Navitimer comes down to your priorities in price, water resistance, design and brand history—not a universal winner.
What is new on the Sinn 903 St II?
The St II updates the 903 navigation chronograph’s bezel operation and construction. Fratello’s July 2024 review describes the earlier design as using a crown at 10 o’clock to operate the bezel; on the St II, you turn the bezel directly at its outside edge. The same review reports that water resistance rose from 100 m on the previous generation to 200 m on the St II. Sinn’s November 2025 product sheet confirms the current rating as 20 bar.
The current black reference has a black electroplated sunburst dial, applied hybrid-ceramic luminous elements, a logarithmic slide-rule bezel, sapphire crystal and a transparent sapphire case back. Sinn’s product sheet also lists low-pressure resistance and a screwable winding crown. The polished and satin-finished stainless-steel case is paired with a column-wheel chronograph movement.
Sinn says the 903 St II received “Watch of the Year 2025” from Armbanduhren magazine; that distinction is reported here as stated in Sinn’s product document.
#1 Best Overall
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How the slide-rule bezel works
The bezel and dial scales form a manual logarithmic calculator. Rotate the bezel to align scale values, then read the corresponding result elsewhere on the scale. Sinn names time, distance and fuel consumption as intended calculation examples. In practice, it is a compact way to work through proportional relationships without reaching for a separate calculator.
It is not a substitute for a certified navigation instrument, flight computer or independently checked calculation. Treat results as a convenience for ordinary calculations, not as safety-critical navigation data.
Rank #2
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Dimensions, movement and functions
| Specification | Sinn 903 St II |
|---|---|
| Case diameter | 41 mm (Sinn, 2025) |
| Case thickness | 14.5 mm (Sinn, 2025) |
| Lug width | 22 mm (Sinn, 2025) |
| Weight | 84 g without strap (Sinn, 2025) |
| Water resistance | 20 bar (Sinn, 2025) |
| Movement | LJP L110 automatic column-wheel chronograph |
| Power reserve | At least 60 hours when fully wound (Sinn, 2025) |
| Other movement details | 26 jewels, 28,800 semi-oscillations per hour and seconds-stop function (Sinn, 2025) |
| Functions | Hours, minutes, subsidiary seconds, date, chronograph and logarithmic slide rule |
For the movement, “at least 60 hours” is Sinn’s stated minimum reserve when fully wound, not an independently measured result. Fratello characterizes the LJP L110 as derived from the Valjoux 7750; that is the reviewer’s description, rather than Sinn’s wording in the product specification.
How it wears: one reviewer’s experience
Thomas Van Straaten of Fratello says he wore the St II for about a week. Although its 41 mm diameter and 14.5 mm thickness initially led him to expect a large-feeling watch, he found it manageable on his 17.5 cm wrist and described its presence as commanding. That is one wearer’s account, not a fit guarantee: wrist shape, preferred fit and strap choice all affect how a watch sits.
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Rank #3
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Van Straaten praised the perceived build quality and bright lume, and found the black version versatile. He also had design reservations, including the appearance of the luminous blocks and the chronograph hand crossing the numeral 12. Those impressions may help frame an in-person try-on, but they remain his preferences.
Sinn 903 St II vs. Breitling Navitimer
The two watches share the navigation-chronograph idea, but a useful comparison depends on a specific Navitimer reference and what matters most to you. Fratello’s judgments about relative design and value are editorial opinions, not objective rankings.
Rank #4
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| Comparison point | Sinn 903 St II | Breitling Navitimer |
|---|---|---|
| Price | Sinn’s November 2025 list: €3,350 on leather or silicone, or €3,650 on a solid bracelet, including tax. | A current like-for-like price is not stated in the sources cited here; compare the exact reference and market before deciding. |
| Water resistance | 20 bar according to Sinn’s 2025 product sheet. | Varies by reference; the cited comparison does not establish a figure for a specific Navitimer. |
| Movement | LJP L110 automatic column-wheel chronograph, with at least 60 hours of reserve when fully wound according to Sinn. | The comparison sources do not establish a like-for-like movement specification for a particular Navitimer reference. |
| Dial and design | Fratello praises the Sinn’s build and value but raises reservations about aspects of its dial and hands. | Fratello considers the Breitling’s element placement and visual hierarchy more refined; this is the reviewer’s aesthetic judgment. |
| History and brand | Monochrome reports that Sinn acquired rights and parts related to the Navitimer 806/809 during Breitling’s late-1970s crisis and later produced the 903 under its own name. | The Navitimer is the historical reference point in that reported account; consider whether its brand identity or Sinn’s take on the format matters more to you. |
The reported history is useful context, but it should not be stretched into a claim that the watches are identical or that the Sinn is simply a Navitimer under another name. For a purchase decision, compare the exact models you are considering and handle both if possible.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Price, straps and buying considerations
Sinn’s November 2025 English product PDF lists prices including tax of €3,350 with a leather strap, €3,350 with silicone, and €3,650 with a solid bracelet. These are a dated Sinn price snapshot, not a promise of today’s local price or availability; regional taxes and retailer terms may differ. The listed warranty is two years.
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Best Value
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- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
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The 22 mm lug width gives you a starting point if shopping for a 22 mm watch strap, but width alone does not guarantee compatibility. Check the attachment and spring-bar arrangement, strap thickness and taper, and whether the buckle or clasp suits the watch. Sinn offers leather, silicone and solid-bracelet configurations in the cited price list. The research cited here does not establish current stock or delivery dates.
Monochrome’s May 2024 launch coverage also describes matte-blue and limited light-blue sibling versions. They are separate references, not the black-dial St II discussed here; check with Sinn or an authorized retailer for current availability and variant-specific details.
Quick Recap
Sources
- Sinn, 903 St II official product information and November 2025 product PDF
- Thomas Van Straaten, Fratello, July 4, 2024: hands-on review
- Monochrome, May 14, 2024: 903 St II launch coverage
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
