Grand Seiko · Quartz

Strap for Quartz Stainless Steel / Black / Bracelet

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

Lug width20 mm
Case diameter37 mm
ReferenceSBGX321
FamilyQuartz
MovementGrand Seiko caliber 9F61 Hours, Minutes, Seconds
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 Quartz SBGX321

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Quartz SBGX321, seen from the bench

The Grand Seiko SBGX321 is a stainless steel quartz watch featuring the 9F61 movement, certified to ±10 seconds per year. The case measures 37.10mm with integrated lugs and lug width of 20mm. This model embodies Japanese watchmaking precision and minimalist design principles, combining professional accuracy with balanced proportions suitable for various wrist sizes.

Frequently asked questions

What is the lug width of the Grand Seiko SBGX321?

The Grand Seiko SBGX321 features a 20mm lug width, compatible with all standard straps of this width. The integrated lugs of the case ensure a clean transition between the watch body and strap.

What is the best strap for the Grand Seiko Quartz SBGX321?

For this model, we recommend crocodile leather in grey or dark blue for formal settings, burgundy shell cordovan for evening wear, or satin-finished calf with vegetable tanning for a versatile look. The choice depends on your use case: shell cordovan develops a natural patina over time, whilst crocodile maintains a more austere appearance.

How do I change the strap on the Grand Seiko SBGX321?

The SBGX321 uses standard 20mm spring bars. Remove the bars using a specialist tool, extract the old strap and insert the new one by sliding the bars into their respective slots. The operation takes a few minutes and is fully reversible.

Can I use a bespoke aftermarket strap?

Yes, absolutely. Milano Straps offers custom straps with bespoke measurements, choice of leathers (crocodile, calf, shell cordovan), initials and stitching thread. The Casati Milano atelier creates straps by appointment with 18-month warranty and direct WhatsApp updates.

How long does a leather strap last on a daily-wear watch?

A quality leather strap with vegetable tanning typically lasts 2-4 years in daily use. Shell cordovan boasts greater longevity thanks to the compactness of its fibres. The natural patina that develops enhances the appeal over time. To extend lifespan, we recommend rotating between multiple straps and protecting the leather from excessive moisture.

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