Zenith · Class

Strap for Class Sport El Primero Stainless Steel / Silver / Bracelet

Takes 18 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width

18mm

18 mm straps All Zenith

Lug width18 mm

Case diameter40 mm

Reference03.0510.400/04.M510

FamilyClass

MovementZenith caliber El Primero 400 Hours, Minutes, Small Seconds | Date | Chronograph, Column wheel

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 Class 03.0510.400/04.M510

Selected for the 18 mm lug width · workshop selection

All 18 mm straps →

The Class 03.0510.400/04.M510, seen from the bench

The Zenith Class 03.0510.400/04.M510 is a 40mm stainless steel sports chronograph powered by the El Primero 400 caliber, featuring a manual column-wheel movement operating at 36,000 vph for precise tenth-of-second timing. The case houses a classical chronograph display with hours, minutes, small seconds, and date function, water-resistant to 100 meters, designed with geometric proportions reflecting Le Locle manufacturing philosophy. The 18mm lug width ensures optimal visual balance and compatibility with aftermarket straps.

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