The Certina DS Action Diver 40.5 is the collection’s new middle size: a 40.50mm, 14.10mm-thick automatic diver rated to 300 metres and certified to ISO 6425:2018. Reference C048.407.18.051.01 combines a 316L stainless-steel case, sapphire crystal and ceramic bezel components with Certina’s Powermatic 80 movement. The size should broaden the watch’s appeal beyond the existing 38mm and 43mm options, although its 14.10mm profile remains substantial for a modern 40mm watch.
What the 40.5mm model changes
Certina describes 40.5mm as a new size for the DS Action line. It sits between the smaller 38mm models and the larger versions, offering a compromise in dial presence and wrist coverage rather than a fundamentally different type of watch. The cited reference has a 20.00mm lug width, so standard 20mm replacement straps are the relevant size; compatibility still needs checking against the particular bracelet or strap end links.
There is no controlled side-by-side wearing test establishing how the 40.5mm model feels against the 38mm or 43mm watches. Wrist shape, lug geometry, bracelet fit and the 14.10mm height will matter as much as the diameter. In practical terms, the 40.5mm case should look less compact than the 38mm and less imposing than the 43mm, but it is not a thin dress-style diver.
Certina DS Action Diver 40.5 specifications
| Specification | C048.407.18.051.01 |
|---|---|
| Movement | Powermatic 80 automatic |
| Case diameter | 40.50mm |
| Case height | 14.10mm |
| Lug width | 20.00mm |
| Case material | 316L stainless steel |
| Crystal | Sapphire |
| Bezel | Ceramic elements; black on this reference |
| Dial | Black on this reference |
| Water resistance | 300m |
| Diver certification | ISO 6425:2018, as stated by Certina |
| Official UK listed price | £790 at the time of publication research; regional prices, tax, stock and retailer pricing can change |
How serious is the dive specification?
Certina states that the watch is certified to ISO 6425:2018 and rated to 300 metres. The standard covers more than a depth number. Certina says its diver requirements include a preselection timing device, legibility in darkness, operation under water, strap and crown resistance, resistance to external forces, salt water and thermal shock, antimagnetic performance, depth-plus-margin water resistance and shock resistance.
#1 Best Overall
- Case Size: 38 mm, Band Width: 13.00 mm, Case Thickness: 38.00 mm
- Automatic movement, Powermatic 80, Nivachron, Index dial type, Date
- Stainless steel bracelet, Double Locking Foldover Clasp
- Water-resistant up to 300 m / 990 ft: suitable for diving and/or snorkeling.
- 2 Year International Warranty
Certina also says each watch is tested in water for three hours as required by ISO 6425. That is the brand’s description of its compliance process, not an independently witnessed laboratory test. No independent long-term pressure, water-ingress or dive results were located for this first look.
Construction supporting the DS Concept
- Sapphire crystal protects the dial.
- An O-ring seals the setting stem.
- A reinforced case back adds protection.
- An ultra-thin dial-support seal helps isolate the dial assembly.
- A screwed movement holder secures the calibre.
Certina says ceramic components are used across the range and describes them as scratch-resistant and hypoallergenic. The cited black model uses a black ceramic bezel component.
Rank #2
- Case size: 40.50 mm: Band Width: 20.00 mm: Case Thickness: 14.10 mm
- Automatic , Powermatic 80, Nivachron, Date
- Band Type: Steel: Band Length: 179.64 mm
- Water-resistant up to 300 m / 990 ft: suitable for diving and/or snorkeling.
- 2 Year International Warranty
New DS Concept Extreme Shock Resistance
The 40.5mm is the first Certina watch identified by the brand as using the next evolution of its DS system, called “New DS Concept Extreme Shock Resistance.” Certina’s launch material says the forces in testing were so extreme that the equipment reached its limits. That is a manufacturer claim; no independent laboratory report was identified to quantify the forces, compare them with competing watches or establish a guaranteed real-world advantage.
The claim is nevertheless significant within Certina’s own range: the 40.5mm model is not merely a resized case, but the launch vehicle for the brand’s updated shock-resistance concept.
Rank #3
- Case Size: 12.20 mm, Band Width: 38.00 mm, Case Thickness: 38.00 mm
- Swiss Automatic movement, Titanium case, DATE, Grey band
- Band Type : Titanium, Band Length: 175mm
- Water-resistant Diver's watch 300m according to ISO 6425:2018
- 2 Year International Warranty
Powermatic 80 movement and model variants
The cited watch uses Certina’s Powermatic 80 automatic movement. The name denotes the movement family’s stated 80-hour power-reserve specification, while the supplied product information does not provide an independent accuracy result for this particular watch. No seconds-per-day figure or long-term reliability test should be assumed.
Certina’s launch material describes four variants. They use titanium or stainless steel cases, with ceramic bezels matched to the dial colours. The black-dial, black-bezel stainless-steel reference covered here is C048.407.18.051.01. Case weight, the exact movement execution in every variant and variant-by-variant pricing are not established in the available product details.
Rank #4
- Case Size: 38.00 mm, Band Width: 19, Case Thickness: 12.20 mm
- Automatic movement, Powermatic 80, Nivachron, Index dial type, Date
- Stainless steel bracelet, Double Locking Foldover Clasp
- Water-resistant up to 300 m / 990 ft: suitable for diving and/or snorkeling.
- 2 Year International Warranty
40.5mm versus 38mm and 43mm
| Comparison point | What is established for the 40.5mm | What to verify on 38mm/43mm models |
|---|---|---|
| Diameter and thickness | 40.50mm diameter; 14.10mm high | Individual model dimensions; do not infer them from diameter alone |
| Lug width and wrist coverage | 20.00mm lug width | Lug length, end-link shape and actual wrist coverage |
| Materials and weight | 316L steel for the cited reference; titanium and steel variants are described across the range | Exact material and resulting weight of each model |
| Bezel and dial choices | Black dial and black ceramic bezel for C048.407.18.051.01 | Colour and ceramic combinations by reference |
| Movement and reserve | Powermatic 80 automatic | Movement designation and documented reserve for each specific reference |
| Price | £790 official UK listing at the cited time | Current regional list and retailer prices |
Choose the 40.5mm if you want a conventional modern dive-watch footprint without moving to the largest case, and if the new DS shock-resistance architecture matters to you. Choose a 38mm model when minimum wrist coverage is the priority, or a 43mm model when maximum dial and case presence is preferred. Those are size-based decisions, not conclusions from a controlled comfort test.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the launch video shows
Certina’s official launch video, “DS Action Diver 40.5mm | Rewriting the rules of diver’s watches,” published 23 May 2025, is useful for visual details: case finishing, bezel action, dial colours and wrist shots. Use those images to judge the design and apparent scale, while relying on the product specifications for the hard measurements, rating and materials. A video wrist shot cannot establish fit for every wrist.
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- Case size: 40.00 mm: Band Width: 20.00 mm: Case Thickness: 11.20 mm
- Quartz , Precidrive
- Band Type: Steel: Band Length: 179.05 mm
- Water-resistant up to 300 m / 990 ft: suitable for diving and/or snorkeling.
- 2 Year International Warranty
Buying considerations
- Confirm that the reference is C048.407.18.051.01 if you want the black steel model specified here.
- Check the selling region: the £790 figure is an official UK listing captured at a particular time, not a universal price.
- Verify stock, taxes, warranty terms and return conditions with the retailer.
- For a strap change, start with the documented 20.00mm lug width and confirm end-link and spring-bar compatibility.
- Do not treat the 300m rating as evidence of an independently conducted dive test; it is Certina’s stated ISO-certified specification.
Verdict
The DS Action Diver 40.5 is a meaningful expansion of Certina’s dive range: it delivers the sought-after middle diameter while retaining a 300m ISO 6425:2018 specification, sapphire crystal, ceramic components and the Powermatic 80 automatic movement. Its 14.10mm height means “mid-size” does not mean slim. The updated DS shock-resistance system is the model’s most notable technical change, but the extreme-testing language remains Certina’s claim rather than an independently quantified result.
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