The documented blue steel Zenith Defy Skyline Skeleton is reference 03.9300.3620/79.I001: a 41 mm automatic skeleton watch with an El Primero 3620 SK movement and a continuously running 1/10th-second indicator. Zenith lists a frequency of 36,000 vibrations per hour (5 Hz), approximately 55 hours of power reserve and 10 ATM water resistance. Those are manufacturer specifications, not independent test results.
“Skyline Skeleton” also covers other configurations, so the reference matters when checking price or comparing specifications. The details below concern the blue steel reference unless stated otherwise.
What is the Zenith Defy Skyline Skeleton?
Zenith’s blue-dial steel Skyline Skeleton pairs the Defy Skyline’s octagonal case and faceted bezel with an openworked dial shaped around the brand’s four-pointed star motif. The visible movement is the automatic El Primero 3620 SK. Zenith describes the design and publishes the technical figures; those claims do not establish how the watch looks or feels in person.
The exact reference documented on Zenith’s UK product page is 03.9300.3620/79.I001. Confirm the reference before applying its specifications to a listing described only as “Defy Skyline Skeleton.”
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What are its specifications?
| Specification | Blue steel reference 03.9300.3620/79.I001 |
|---|---|
| Case | 41 mm stainless steel, with an octagonal shape and faceted bezel; Zenith specification |
| Dial | Blue openworked dial; Zenith description |
| Movement | El Primero 3620 SK automatic skeleton movement; Zenith specification |
| Frequency | 36,000 vibrations per hour (5 Hz); Zenith specification |
| Power reserve | Approximately 55 hours; Zenith specification |
| Functions | Central hours and minutes, plus a continuously running 1/10th-second indicator; Zenith specification |
| Water resistance | 10 ATM; Zenith rating |
| Bracelet and strap | Steel bracelet and an additional blue patterned rubber strap, with an interchangeable strap system; Zenith product listing |
These figures come from Zenith’s product page and are not independent measurements. The 10 ATM rating is the published water-resistance specification; it does not, by itself, establish a particular activity recommendation.
What does the 1/10th-second indicator do?
The indicator is a continuously running part of the display, rather than a conventional seconds hand that makes one sweep per minute. Zenith pairs it with the movement’s stated 5 Hz frequency. The openworked construction makes the movement part of the dial’s visual layout, but the available product specifications do not establish legibility in different lighting or how the indicator performs in everyday use.
What comes with the watch?
For the blue steel reference, Zenith lists a steel bracelet and an additional blue patterned rubber strap, along with an interchangeable strap system. The listing supports those included components; it does not verify fit or clasp compatibility for third-party replacement straps. Confirm compatibility for the exact reference before buying one.
How does this version differ from other Skyline Skeletons?
Zenith’s Skyline Skeleton family includes different materials, dials and regional editions. Their specifications and prices should not be transferred to the blue steel reference.
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| Configuration | What Zenith lists | Why the distinction matters |
|---|---|---|
| Blue steel, 03.9300.3620/79.I001 | 41 mm steel case, blue openworked dial, approximately 55-hour reserve, 10 ATM; Zenith UK product page | This is the reference covered in the main specifications above. |
| Middle East edition, 03.9304.3620/07.1001 | 41 mm stainless-steel case, golden-tone dial, El Primero 3620 SK, 60-hour listed reserve, 10 ATM and production limited to 100 pieces for the Middle East; Zenith press release, 2025 | A separate edition with a different reference and stated reserve, not a specification update for the blue model. Zenith’s 2025 announcement identifies this regional variant. |
| White ceramic Skyline Skeleton configurations | Zenith’s US collection page lists white ceramic models; the exact specifications and prices vary by configuration | They are material and price alternatives, not steel versions of reference 03.9300.3620/79.I001. See Zenith’s US Skyline collection. |
What is the price?
There is no verified exact current US price for reference 03.9300.3620/79.I001 in the cited material. Zenith’s US collection page displays $12,300 and $18,900 for different Skyline Skeleton configurations, but those amounts cannot be assigned to the blue steel reference without an exact-reference listing in the relevant market. Check the local Zenith page or an authorized retailer for current price and availability.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What can a hands-on review establish?
The product information establishes the design description, components and manufacturer-listed specifications, but it cannot support firsthand conclusions about wrist comfort, finishing, readability, clasp feel, strap-change ease, accuracy or observed timekeeping. Those require direct inspection or testing; no such results are claimed here.
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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.
