Seiko · Prospex Divers

Strap for Prospex Diver 1970 Save the Ocean

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

Lug width20 mm
Case diameter43 mm
ReferenceSPB301
FamilyProspex Divers
MovementSeiko caliber 6R35 hours, minutes, seconds | date
Year2022
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 Divers SPB301

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Prospex Divers SPB301, seen from the bench

The Seiko Prospex Divers SPB301 features the automatic caliber 6R35 with hour, minute, second and date indication. The watch has 20mm lugs and belongs to the Japanese brand's dive collection. The movement offers essential functions for sports and professional use.

Frequently asked questions

What is the exact lug width of the Seiko Prospex Divers SPB301?

The lug width of the Seiko Prospex Divers SPB301 is 20 mm. This is the precise measurement between the watch lugs where the strap must be inserted. You can verify this using a digital calliper or thickness gauge positioned perpendicular to the lugs.

Which strap is most suitable for the Seiko Prospex Divers SPB301?

It depends on primary use. For formal contexts, an alligator or vegetable-tanned leather strap enhances the watch's character. For underwater activities or summer use, NATO or rubber offer water resistance and durability. For daily balance, honey-toned calf leather combines aesthetics and functionality.

How do I change the strap on my Seiko Prospex Divers SPB301?

Changing the strap requires a spring bar tool to remove the connecting pins. Position the tool in the spring's groove, gently push until it retracts, then extract the strap. Align the new strap with the lugs and release the spring. If unfamiliar with the process, consult a professional.

Are aftermarket straps compatible with the Seiko Prospex Divers SPB301?

Yes, all straps with 20 mm lug width are compatible. However, choose specialised makers who guarantee precise tolerances and construction quality. A poor-quality strap, even if it fits, can damage the watch's lugs over time.

How long does a natural leather strap last on the Seiko Prospex Divers SPB301?

With genuine vegetable tanning and moderate use, a leather strap lasts 3-5 years before showing evident wear. With regular care (periodic cleaning, natural wax conditioning), durability extends to 7-10 years. Constant exposure to water and perspiration significantly reduces longevity.

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.

Request an appointment →

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