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Grand Seiko · Mechanical

Strap for Automatic Hi Beat 36000 GMT Stainless Steel / Red / Bracelet / Dawn of Mt. Iwate

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

Lug width

20mm
20 mm strapsAll Grand Seiko
Lug width20 mm
Case diameter40 mm
ReferenceSBGJ021
FamilyMechanical
MovementGrand Seiko caliber 9S86 Hours, Minutes, Additional 24 Hour Hand (adjustable), Seconds | Date
CaseStainless Steel

Spring bar

Swiss Standard universal spring bars

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

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Straps for the Mechanical SBGJ021

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Mechanical SBGJ021, seen from the bench

The Grand Seiko SBGJ021 is equipped with the mechanical caliber 9S86 which offers hours, minutes, seconds, date and an adjustable GMT hand for the second time zone. The automatic movement features a power reserve and high-precision mechanisms typical of the Grand Seiko manufacture. The reference belongs to the brand's Mechanical collection, designed for enthusiasts of precision mechanical watchmaking.

Frequently asked questions

What is the exact lug width of the Grand Seiko Mechanical SBGJ021?

The lug width of the SBGJ021 is 20 millimetres. This measurement is taken as the internal distance between the two lugs on the watch case and is essential for ensuring correct fit of any aftermarket strap. Always verify this measurement physically before purchasing a replacement strap, and consult the official Grand Seiko documentation if in doubt.

Which strap material is most suitable for the Grand Seiko Mechanical SBGJ021?

The most appropriate material depends on your intended use. For formal elegance, alligator leather in dark brown or black emphasises the understated character of the Mt. Iwate dial. Shell cordovan offers remarkable tactile richness and develops a patina that evolves with time. For daily versatility, vegetable-tanned calf leather provides durability and character. Rubber or NATO fabric straps add sporty versatility whilst maintaining full legibility of the dial.

How do I change the strap on the Grand Seiko SBGJ021?

Remove the strap by unscrewing or extracting the spring bars that secure it within the lugs. Use a dedicated strap removal tool, typically a thin lever designed for this purpose. After removing the old strap, guide the new strap's spring bars into the lateral recesses of the lugs. Ensure the strap is centred before fully securing the spring bars.

Are bespoke artisanal straps compatible with the SBGJ021?

Yes, bespoke straps in 20mm are fully compatible with the SBGJ021. Custom straps from ateliers such as Casati Milano not only guarantee dimensional compatibility but also offer personalisation of leather type, thickness, stitch colour and lug finishing. The precision of artisanal craftsmanship allows for calibrations that mass-produced straps cannot match.

How long does a leather strap typically last on a watch like the SBGJ021?

Durability varies depending on material and usage patterns. A quality artisanal alligator or shell cordovan strap typically lasts 3–5 years with moderate daily wear. Vegetable-tanned leather offers comparable resistance whilst developing a more pronounced patina. Humidity, temperature and cleaning frequency all influence longevity. Artisanal straps from Casati Milano include an 18-month guarantee and can be restored or repaired in case of premature wear.

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