Case #746 — Oris Aquis Cal 400 Ref. 01 400 7763 4135-07 8 24 09PEB

Case #746 — Oris Aquis Date Calibre 400 43.5 mm

Ref. 01 400 7763 4135-07 8 24 09PEB

Status: Available

Condition: Good Pre-Owned

Scope: Box, Manuals, and WatchMaxx Card (No Original Oris Warranty Card)

🔎 Case Notes

Some dive watches earn attention through heritage. This one earned it through engineering. The Aquis Date Calibre 400 43.5 mm was the first watch to carry Oris's in-house, antimagnetic, five-day automatic — the movement that fundamentally changed what the brand could claim against far more expensive competition.

Visually, it is the Aquis at its most cohesive: a blue sunburst dial with applied stick indices, framed by a matching blue ceramic bezel insert and a multi-piece stainless steel case. The dial and bezel read as a single tonal statement rather than two separate components, which is a large part of why this particular configuration remains the default recommendation when collectors discuss the Aquis line.

This example is graded Good Pre-Owned and wears its history honestly. The bracelet clasp shows signs of heavy use and the bracelet itself shows medium use. The case sides show some use. Notably, the sapphire crystal and the ceramic bezel are clean — the two surfaces most visible from above, and the two most expensive to put right.

The watch arrives as a WatchMaxx kit, meaning there is no original Oris warranty card. It is accompanied by the WatchMaxx card, the original presentation box, and the manuals. The year of manufacture is not documented. The bracelet is currently sized to fit an approximately 7¾-inch wrist.

🕰️ The Evidence

• Reference: 01 400 7763 4135-07 8 24 09PEB
• Model / Collection: Oris Aquis Date Calibre 400
• Year: Unknown
• Case: Multi-piece stainless steel case, ceramic minutes scale top ring
• Case Diameter: 43.50 mm
• Thickness: Approximately 13.7 mm
• Lug-to-Lug: Approximately 50 mm
• Lug Width: 24 mm interhorn width
• Dial: Blue, applied stick indices, luminous hands and markers
• Crystal: Sapphire, domed on both sides, anti-reflective coating inside
• Bezel: Blue ceramic, unidirectional rotating diver's bezel
• Crown: Stainless steel, screw-down
• Caseback: Stainless steel, screwed, see-through sapphire glass
• Movement: Oris Calibre 400, automatic winding, Ø 30.00 mm, 28'800 A/h (4 Hz), 21 jewels
• Power Reserve: 120 hours (five days)
• Functions: Centre hands for hours, minutes and seconds; date window with instantaneous date, date corrector and stop-seconds
• Water Resistance: 30 bar (300 metres)
• Bracelet: Multi-piece stainless steel bracelet
• Clasp: Security folding clasp with extension
• Bracelet Fit: Approximately 7¾-inch wrist
• Condition: Good Pre-Owned — heavy use on the bracelet clasp, medium use on the bracelet, case sides show use; crystal and bezel are clean
• Factory Warranty: None claimed — no original Oris warranty card accompanies this example
• Included: Original presentation box, manuals, and WatchMaxx card

🌟 Collector Provenance

The Aquis has been Oris's commercial anchor for well over a decade, but for most of that run it was a Sellita-based proposition — capable, well finished, sensibly priced, and mechanically unremarkable. The parallel 43.5 mm Aquis Date running the Oris calibre 733, based on the Sellita SW 200-1, sat at a materially lower retail price, and that gap defines what this reference actually represents within the family.

Oris positions this 43.5 mm Calibre 400 Aquis as a landmark watch and the first to carry the in-house, antimagnetic, five-day automatic. That makes the reference a genuine inflection point in the model's history rather than simply another dial variant: it is where the Aquis stopped being an entry-level Swiss diver with a stock movement and became the vehicle for Oris's most significant piece of independent engineering.

Within the Calibre 400 Aquis range, the blue dial with matching blue ceramic bezel on steel bracelet is the reference collectors tend to default to — the configuration that most clearly articulates the design. The 43.5 mm case is the larger of the two sizes offered; the Aquis Date with Calibre 400 is available in both 41.5 and 43.5 mm, and the bigger case carries the broader bezel and the more assertive proportions that have characterised the Aquis since its modern redesign.

🌟 Technical Provenance

The Calibre 400 story is worth understanding properly, because it is the reason this watch exists. Calibre 400 is an entirely new movement, independently conceived by Oris; it has a five-day power reserve, is highly resistant to magnetism, and comes with 10-year recommended service intervals and a 10-year warranty.

The power reserve is not achieved by slowing the balance. Designed for intermittent wear, it uses twin barrels with extended mainsprings, each storing two-and-a-half days of power, while running at a conventional 4 Hz. Oris focused on reducing torque in the mainspring to conserve power and reduce pressure on moving parts, and introduced a new gear-train wheel design; the calibre retains 85 per cent of the energy transferred from the mainspring against a norm of around 70 per cent.

Antimagnetism was the second pillar. Oris engineered the movement with more than 30 non-ferrous and anti-magnetic components, including a silicon escape wheel and a silicon anchor. It deviated less than 10 seconds a day after exposure to 2,250 gauss, surpassing ISO 764 standards. Oris's stated rate specification for the calibre is -3/+5 seconds a day — a factory specification, not a measurement taken on this individual watch.

🧾 From the Case File

Practically, this is a watch built to be left alone and picked up again. A five-day reserve means a Friday-evening removal and a Wednesday-morning return without resetting anything — the single most useful real-world property a mechanical watch can have for someone who rotates between pieces. The instantaneous date with quick-set corrector and stop-seconds means that when you do reset it, it takes seconds.

The 30 bar / 300 m rating with screw-down crown and unidirectional bezel is genuine dive specification, and the security folding clasp with extension handles a wetsuit or a swollen summer wrist without tools. The 24 mm interhorn width is broad, which keeps the case visually balanced but does narrow strap options — worth knowing if you intend to swap.

At 43.50 mm with an approximately 50 mm lug-to-lug, this sits firmly in large-diver territory and suits wrists of roughly 7 inches and up. It is currently sized for an approximately 7¾-inch wrist, which should allow adjustment in either direction for most buyers.

Condition should be weighed openly. This is a Good Pre-Owned example: the clasp has seen heavy use, the bracelet medium use, and the case sides show wear. What it has in its favour is that the crystal and ceramic bezel — the elements that most affect how a watch presents at arm's length, and the costliest to replace — are clean. For a buyer who intends to actually wear a 300 m diver rather than preserve one, that is a sensible distribution of wear.

🗝️ BST Verdict

A working example of the watch that reset expectations for Oris — the 43.5 mm Aquis in its most recognisable blue-on-blue configuration, carrying the in-house Calibre 400 and its five-day, antimagnetic specification.

It is honest about what it has been through. The clasp and bracelet show real use and the case sides are not fresh, but the ceramic bezel and sapphire are clean, and the mechanical proposition underneath is unchanged. For someone who wants the Calibre 400 Aquis as a wearer rather than a showpiece, that is the trade worth making.

Supplied with its original presentation box, manuals, and WatchMaxx card. No original Oris warranty card accompanies this watch, and no factory warranty is claimed.

👉 Every case deserves a closer look.