Technical Archive

Casio
G-Shock GA-100 GA-100-1A1

Casio G-Shock GA-100 GA-100-1A1: strap made to measure on the watch at the Casati Milano atelier, by appointment.

GA-100-1A1 Black Black

Technical Specifications

Casio GA-100-1A1
Reference

GA-100-1A1

Movement

Casio caliber 5081 World Time | Perpetual Calendar | Chronograph, Countdown | Alarm

The Heritage

The GA-100-1A1 Black Black is an iconic G-Shock model launched in 1983, featuring an oversized resin reinforced case and integrated bracelet with urban-tactical design. The monolithic construction requires custom artisanal adaptation for strap personalization through specialized bespoke services.
Made to Measure

The strap for this watch is made to measure

On the Casio G-Shock GA-100 the bracelet is drawn as part of the case: no catalogue strap will fit. In the atelier we take the measurements on the watch itself and build the strap on the piece — that is the work of Casati Milano.

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FAQ

Can you fit a standard strap on the Casio G-Shock GA-100 GA-100-1A1?

No, the bracelet is integrated into the case — the lugs are proprietary and a standard strap won't attach. I've seen many failed attempts. To personalise it, I build a custom strap directly onto the watch, in the atelier.

How does the custom strap work for this model?

We work by appointment only at <a href="/pages/casati-booking">Casati Milano</a>. I take measurements directly from the case, study the geometry of the integrated lugs, and create a strap that fits perfectly, respecting the original architecture.

Which leather do I recommend for a G-Shock GA-100?

I prefer robust vegetable-tanned leather — it has the sporty character this watch deserves. It ages beautifully, develops authentic patina, and resists daily wear without failure. I avoid leather that's too soft: this model has a technical soul.

How long does a well-made strap last?

A quality vegetable-tanned leather strap lasts years — I've seen them wear well for 5, 6 years with conscious use. Leather needs air and light maintenance; if you stress it daily without care, it ages differently. What matters is respect for the material.

Why is the GA-100 so tough?

It was born from a 1983 challenge: Casio wanted an indestructible watch. The reinforced resin case and integrated bracelet came from that philosophy. For the owner, it means having a real tool — not an accessory. A custom strap transforms it without betraying its soul.