Seiko · Prospex Sky

Strap for Prospex Sky SSC425P1 Stainless Steel / Cream

Takes 20 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width20 mm
Case diameter44 mm
ReferenceSSC425P1
FamilyProspex Sky
MovementSeiko caliber V176 hours, minutes, seconds | Chronograph, Rattrapante | solar charging
CaseStainless Steel

Spring bar

Swiss Standard universal spring bars

The right category for this model · 316L steel, all lug widths 13–26 mm

Straps for the Prospex Sky SSC425P1

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Prospex Sky SSC425P1, seen from the bench

The Seiko Prospex Sky SSC425P1 features the V176 solar-powered chronograph movement with split-second function. The movement offers hours, minutes and seconds indications powered by solar energy. The watch has 20mm lugs for the strap.

Frequently asked questions

What is the exact lug width of the Seiko Prospex Sky SSC425P1?

The lug width of the Seiko Prospex Sky SSC425P1 is 20 millimetres. This dimension is standard in the sports watch segment and allows you to pair a vast range of artisanal straps. To verify the measurement, measure perpendicularly the distance between the inside of one lug and the inside of the other, at the level of the contact line with the case.

What is the best strap for the Seiko Prospex Sky SSC425P1?

The choice depends on intended use. For daily elegance, we recommend a vegetable-tanned leather strap in dark brown or tobacco, which softens the sporty character of the 44mm. For nautical and extreme outdoor applications, a Cordura nylon NATO or an FKM rubber strap guarantees moisture resistance and quick drying. A matte alligator model maintains the technical spirit while elevating refinement.

How do you change the strap on a Seiko Prospex Sky SSC425P1?

The strap of the SSC425P1 is replaced using a dedicated tool (spring bar tool) or a spring extractor. Position the watch with the lugs facing towards you, insert the flat tip of the tool into the appropriate slot under the lug, gently push towards the opposite side to compress the internal spring, and slide the strap out. Repeat for the other lug. Installation of the new strap follows the reverse process: align the ends with the lug holes and push until you hear the spring latch click closed.

Is an aftermarket strap compatible with the Seiko Prospex Sky SSC425P1?

Yes, any strap with a 20mm lug width is compatible with the SSC425P1. MilanoStraps artisanal straps, crafted to specification for this width, fit perfectly onto the Seiko case lug attachments. Compatibility is guaranteed by industrial standardisation of lug width, regardless of strap brand.

How long does a leather strap last on the Seiko Prospex Sky SSC425P1?

Durability depends on material and use. A quality vegetable-tanned leather strap, with proper care (protection from salt water, regular drying, annual conditioning), lasts 5-7 years in continuous use. Alligator models can exceed 10 years. FKM rubber straps have shorter lifespan (3-5 years) as the material hardens over time, but are replaceable at modest cost. Wear is subjective and correlated to frequency of use, exposure environment, and maintenance.

The next step

The right strap isn't chosen. It is built, together.

From the atelier appointment to delivery, every step is made for those who know that things done well take time. Rare leathers, one piece at a time, eighteen months of warranty.

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Casati Milano · Via XX Settembre 15, Milan · by appointment only