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Zenith Defy Skyline Skeleton Steel 41mm Blue
Ref. 03.9300.3620/79.I001
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Stepping up in Zenith's range
The octagonal stainless steel case measures 41mm across and 11.5mm to 12.2mm thick, with a bezel cut into brushed and polished facets. The blue skeleton dial is shaped around Zenith's four-pointed star motif, leaving the movement visible beneath. Rhodium-plated, faceted hands carry Super-LumiNova C1, and a 1/10th of a second counter at 6 o'clock completes a full rotation every ten seconds. The El Primero 3620 SK runs at 36,000 vibrations per hour with a power reserve of 55 to 60 hours. A domed sapphire crystal with double-sided anti-reflective treatment sits above, while a sapphire exhibition caseback reveals the movement from behind. The stainless steel bracelet fastens with a folding clasp.
- Reference
- 03.9300.3620/79.I001
- Brand
- Zenith
- Collection
- Defy
- Case size
- 41mm
- Case thickness
- 11.5mm
- Case material
- Stainless steel
- Case shape
- Octagonal
- Dial
- Blue
- Crystal
- Sapphire
- Movement
- Automatic
- Calibre
- El Primero 3620 SK
- Functions
- Skeleton dial
- Water resistance
- 100m
- Bracelet / strap
- Stainless steel bracelet
- Strap colour
- Blue
- Clasp
- Folding clasp
- Lume
- Super-LumiNova
- Retailer
- Mappin & Webb
Additional specifications
- Power reserve
- 55 hours
Learn more about Zenith
Georges Favre-Jacot founded Zenith in Le Locle in 1865, aged twenty-two, with an idea that was radical for the Swiss industry: bring every trade needed to make a watch — movement, case, dial, hands — under one roof and one management. The integrated manufacture was largely his invention, and the Le Locle site he built is still in use.
The approach produced results at observatory trials, where Zenith accumulated more precision awards than any other manufacture. The name itself came from a calibre Favre-Jacot considered the summit of his work.
Its defining achievement is the El Primero of 1969, developed over seven years and announced in the same year as the Heuer-Breitling consortium's Calibre 11 and Seiko's 6139. It was an integrated automatic chronograph beating at 36,000 vibrations per hour, allowing measurement to a tenth of a second — a frequency almost nothing else matched for decades.
It nearly did not survive. When American owners ordered the mechanical tooling scrapped during the quartz crisis, a watchmaker named Charles Vermot hid the plans, presses, and cams in a walled-off attic. When demand for mechanical chronographs returned, Zenith could restart production because of him. Rolex used the El Primero in the Daytona from 1988 to 2000.
LVMH acquired Zenith in 1999.
- 1865
- Georges Favre-Jacot founds the integrated manufacture at Le Locle.
- 1969
- The El Primero automatic chronograph debuts at 36,000 vph.
- 1975
- Charles Vermot hides the El Primero tooling from destruction.
- 1988
- Rolex adopts the El Primero for the Daytona.
- 1999
- Acquired by LVMH.
Also in 6 collections
This watch appears in the Zenith Defy range (23), Back in Stock (2,812), Stainless Steel Watches (2,706), Automatic Watches (1,549), Blue Dial Watches (735) and Skeleton Watches (271).
Temporarily out of stock
Mappin & Webb is not currently taking orders for this reference. Last listed as available on 14 September 2026. Stock is checked nightly and this page updates when it returns.
What the specifications mean
A mechanical watch for everyday wear.
Strengths
- 100m water resistance covers swimming and watersports
- Sapphire crystal, which resists scratching
- Luminous hands and markers for low light
- Sits in the lower half of Zenith's range as we list it
Zenith Defy Skyline Skeleton Steel alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | 03.9300.3620/79.I001 | N3003.26X01.B01.R01 | 103928 |
|---|---|---|---|
| Price | £10,600 | £9,700 | £9,400 |
| Case size | 41mm | 41mm | 41mm |
| Water resistance | 100m | 100m | 100m |
| Movement | Automatic | Automatic | Automatic |
| Strap | Stainless steel bracelet | Rubber strap | Stainless steel bracelet |
| Power reserve | 55 hours | 65 hours | 42 hours |
| This watch | Closely matched | Closely matched |
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 100m it is rated for swimming and snorkelling, though not for diving.
Water resistance explainedWill the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Sapphire, mineral and acrylic comparedDoes it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
Quartz, automatic and solar comparedHow long does it run for when it's not worn?
About 55 hours fully wound — enough to survive a night off the wrist, but not a full weekend.
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