The new Sinn 903 St II is a technically redesigned 41 mm automatic navigation chronograph. It retains the series’ distinctive logarithmic slide-rule bezel and aviation-instrument layout, while moving bezel control to the case exterior, adding hand-applied hybrid-ceramic luminous elements and updating the case and movement package. The black-dial St II is offered alongside the blue-dial 903 St B E II.
What is new on the Sinn 903 St II?
Sinn describes the latest 903 as “technically completely redesigned.” The most visible functional change is the bezel: it can now be operated smoothly from the watch’s outer diameter instead of by using the additional crown arrangement found on the previous design. The navigation-chronograph dial layout remains familiar.
Legibility has also been revised. Hybrid-ceramic luminous elements are hand attached to the indices, the 12, and the hour and minute hands. Sinn’s catalogue describes the result as “extreme brightness and perfect readability in the dark.”
The case keeps the practical aviation-watch proportions but uses a modern polished-and-satinised stainless-steel construction, sapphire front and display back, and 20-bar water resistance.
#1 Best Overall
- Case Size: 41.00 mm, Band Width: 20, Case Thickness: 13.67 mm
- Mechanical movement, 316L stainless steel case with black PVD coating, Index dial type,
- Stainless steel strap/bracelet, interchangeable quick release bracelet,folding clasp with safety and push-buttons closure
- Water-resistant up to a pressure of 10 bar (100 m / 330 ft)
- 2 Year International Warranty
Sinn 903 St II specifications
| Specification | 903 St II detail |
|---|---|
| Case material | Polished and satinised stainless steel |
| Diameter | 41 mm |
| Thickness | 14.5 mm |
| Lug width | 22 mm |
| Weight | 84 g without strap |
| Crystal | Front sapphire crystal with anti-reflective treatment |
| Case back | Transparent sapphire display back |
| Water resistance | 20 bar; also resistant to low pressure |
| Movement | Automatic La Joux-Perret LJP L110 |
| Movement features | Column-wheel chronograph, seconds-stop function, 26 jewels |
| Frequency | 28,800 semi-oscillations per hour (4 Hz) |
| Power reserve | Approximately 60 hours, as stated by Sinn Japan’s current listing |
| Anti-magnetism | 4,800 A/m under DIN 8309 |
| Warranty | Two years |
What the 903 St II can do
Chronograph timing
The LJP L110 records elapsed time with a central chronograph seconds hand, a 30-minute counter and a 12-hour counter. Its column-wheel control is a traditional mechanical architecture intended to give the start, stop and reset sequence a clearly defined feel. A seconds-stop function allows the running seconds hand to be halted when the crown is pulled for more precise setting.
Everyday calendar and time display
Alongside the chronograph, the watch provides hours, minutes, subsidiary seconds and a date display.
Rank #2
- 59 teeth gear for 29 ½ Days MoonPhase Display
- Bi-directional Bezel
- Column Wheel Chronograph
- Blue steel screws
- Exhibition Case Back Cover
Logarithmic slide-rule bezel
The external logarithmic bezel is the defining navigation feature. By aligning values on its scales, the wearer can perform multiplication and division and estimate relationships involving time, distance and fuel consumption. For example, a known distance and elapsed time can be compared to derive speed; fuel used over a known distance can be compared to estimate consumption. These are manual calculations, so the result depends on reading the scales correctly and on having reliable input figures.
The redesigned bezel operation is intended to make those calculations easier to set up while the watch is on the wrist. It is a calculation aid rather than an electronic flight computer and does not replace certified cockpit instruments or navigation procedures.
Recommended Free Tools
Rank #3
- Seagull St1901 Movement: Equipped with the original Seagull ST1901 manual-winding mechanical movement, ensuring precision and reliability.
- 1963 Chronograph: Inspired by the 1963 pilot's watch, this chronograph features a classic aviation design with a diameter of 40 mm.
- Sapphire Glass & 50m Waterproof: Sapphire glass and 50m waterproof rating provide durability and protection against scratches and waterprof.
- Watch Features: The diameter of the watch is 40mm, the thickness is 13mm, and the strap width is 20mm. Display back cover,feel the beauty of mechanical motion.Super Luminous dial and luminous pointer for easy reading in low light conditions.
- Comfortable Leather Strap: Equipped with a comfortable leather strap, perfect for daily wear and sports activities.
How large does the new Sinn 903 wear?
The 41 mm diameter and 22 mm lug width place the 903 St II in the contemporary sport-chronograph range. Its 14.5 mm thickness reflects the automatic chronograph movement and slide-rule bezel. At 84 g without a strap, it is substantial without the mass of a full steel bracelet. Wrist fit will depend on lug shape, strap choice and wrist circumference; the published dimensions do not establish how it will feel on every wrist.
903 St II versus 903 St B E II
Sinn’s current Series 903 page lists two models: the black-dial 903 St II and the blue-dial 903 St B E II. They share the generation’s navigation-chronograph concept, but the dial colour is the immediate visual distinction. The available product material does not state a separate movement, case size, water-resistance rating or power-reserve figure for the blue model, so those items should not be assumed to differ.
Rank #4
- Precise Time Keeping:Automatical Mechanial Self-Winding Movement, provide precise and accurate time keeping. Fully winded, the power reserve of your watch can reach 36 hours.
- Stainless steel case with a black leather strap. Fixed bezel.Date display at the 3 o'clock position. Automatic movement.
- Fashion Casual Design: Analog display design with 12 Arabic numerals, very easy to read time. Leather band with the simplicity of business casual. Also make it a great gift for family or friends.
- Waterproof For Daily Use: Mildly Water Resistant NOTE:Only resistant splash or drip, not suitable for shower, swimming and diving. Too much water contact or usage in extreme Hot or Cold temperature will shorter watch life.
- Comfort: The strap is soft and comfortable and environmental friendly.
| Comparison point | 903 St II | 903 St B E II |
|---|---|---|
| Dial colour | Black | Blue |
| Luminous treatment | Hand-applied hybrid-ceramic luminous elements on indices, 12, hour and minute hands | Generation-specific treatment is listed by Sinn; separate variant detail is not stated in the supplied product material |
| Case and wear dimensions | 41 mm × 14.5 mm; 22 mm lugs; 84 g without strap | Not stated separately; do not assume a dimensional difference without checking the regional listing |
| Movement | La Joux-Perret LJP L110 automatic column-wheel chronograph | Not stated separately in the supplied material |
| Slide-rule bezel | Externally operable logarithmic bezel | Series 903 navigation-bezel function; variant-specific usability detail is not stated |
| Water resistance | 20 bar and low-pressure resistant | Not stated separately in the supplied material |
| Display back | Transparent sapphire | Not stated separately in the supplied material |
| Warranty | Two years | Not stated separately in the supplied material |
| Current price | From €3,350 including tax on leather or silicone; €3,650 on a solid bracelet (November 2025 official product sheet) | Not stated in the supplied current-price material |
Choose between them primarily by dial preference, then confirm the exact strap, bracelet, dimensions, price and availability for your region before ordering.
Price and what the configuration changes
Sinn’s November 2025 product sheet lists the 903 St II at €3,350 including tax on a leather or silicone strap and €3,650 on a solid bracelet. The €300 difference is therefore a configuration premium for the bracelet version, not a different movement or a higher water-resistance rating.
Best Value
- SAPPHIRE CRYSTAL AND 5ATM WATER RESISTANCE. This mechanical watch features a highly durable synthetic sapphire crystal. It offers superior scratch resistance to maintain exceptional dial clarity. With an enhanced 5ATM waterproof rating, it easily withstands rain, sweat, hand washing, and daily splashes, preventing internal moisture and ensuring longevity in varied environments.
- HISTORICAL AVIATION CHRONOGRAPH FOR EVERY OCCASION. Designed with an authentic retro pilot style inspired by the China’s first military aviation watch, Seagull 1963, this manual winding watch features a fully functional stop watch with 21,600 VPH accuracy. It perfectly transitions from formal business meetings and professional work settings to casual daily wear or travel. The classic design adds a premium vintage touch to your wardrobe, making it a reliable conversation piece.
- HIGH FINISHING ST1901 MOVEMENT SPECIFICATIONS. Built upon a 316L stainless steel round case with a net weight of 58g. Housing an official high finishing ST1901 manual winding movement with 22 jewels and a frequency of 21,600 beats per hour. Features a precise column wheel and horizontal clutch system. Product dimensions: case diameter of approximately 37.3mm, case thickness of 14.7mm, lug to lug distance of 47mm, premium leather strap with a length of 19cm and width of 18mm, completed with a secure pin buckle.
- THE PERFECT TIMEPIECE PRESENT FOR MEN. This mechanical chronograph is tailored for watch enthusiasts, collectors, history buffs, and professionals who appreciate vintage aesthetics and mechanical art. Delivered in an elegant packing box, it serves as a sophisticated present choice for fathers, husbands, brothers, or colleagues on birthdays, anniversaries, graduations, fathers day, or special milestones.
- TWO YEAR WARRANTY AND RELIABLE COMMITMENT. We stand behind the precise craftsmanship of our mechanical wristwatches. Each piece is meticulously inspected to ensure optimal accuracy and performance. Your purchase includes a comprehensive 2 year warranty against movement defects, providing you with long term security and dependable customer support whenever you need assistance.
Monochrome reported introductory 2024 pricing of €3,250 on leather and €3,550 on steel, with deliveries expected in summer 2024. Those were launch prices; the later official Sinn sheet is the more relevant reference for current-price context. Regional tax treatment, stock and currency conversion can change the amount a buyer actually pays.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is the 903 St II worth its price?
Its value rests on a specific combination rather than on size alone: a column-wheel automatic chronograph, a functional logarithmic bezel, sapphire crystals on both sides, 20-bar water resistance, modern luminous execution and a redesigned operating system. Buyers who will use or appreciate the slide rule and aviation-instrument design have a clear reason to choose it.
If the slide-rule function is only decorative to you, the 903 St II’s extra complexity and 14.5 mm thickness may be less compelling than a simpler chronograph. The bracelet price should be judged separately from the watch itself, since the movement and core specifications remain the same. The blue 903 St B E II is the alternative when its colourway better suits your preference, but its regional pricing and configuration need to be verified directly.
Who is the new 903 for?
- Navigation-watch enthusiasts: the external slide-rule bezel preserves the series’ defining identity.
- Mechanical-chronograph buyers: the LJP L110 combines automatic winding with a column-wheel system and 4 Hz operation.
- Frequent travellers and active wearers: 20-bar resistance, low-pressure resistance and sapphire protection provide a broad everyday specification.
- Legibility-focused users: the hand-applied hybrid-ceramic luminous elements are the major readability update.
Before buying
- Decide whether the black 903 St II or blue 903 St B E II suits your dial preference.
- Choose leather, silicone or the solid bracelet; the official St II price difference between strap and bracelet is €300 including tax.
- Check the 41 mm diameter, 14.5 mm thickness and 22 mm lug width against your wrist and existing straps.
- Confirm your region’s current tax-inclusive price, stock and warranty terms with Sinn or an authorised retailer.
- If you intend to use the slide rule, practise the scale alignment for speed, distance and fuel-consumption calculations before relying on it for real-world decisions.
Verdict
The Sinn 903 St II is a specification-rich mechanical navigation chronograph that modernises the series without abandoning its slide-rule purpose. The decisive choices are whether you value that instrument-like functionality, whether the black dial is preferable to the blue 903 St B E II, and whether the bracelet’s €300 premium is worthwhile for your use.
Quick Recap
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.
