Zenith · El Primero

Strap for El Primero Chronomaster 38 Stainless Steel / Blue / Bracelet

Takes 19 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width19 mm
Case diameter38 mm
Reference03.2150.400/53.M2150
FamilyEl Primero
MovementZenith caliber El Primero 400 hours, minutes, small seconds | date | Chronograph, column wheel
Year2017 - 2021
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 El Primero 03.2150.400/53.M2150

Selected for the 19 mm lug width · workshop selection

All 19 mm straps →

The El Primero 03.2150.400/53.M2150, seen from the bench

The Zenith El Primero 03.2150.400/53.M2150 is a 38mm stainless steel chronograph representing a modern interpretation of Zenith's integrated chronograph heritage dating to 1969. The El Primero 400B caliber delivers 50 hours of power reserve and 36,000 vph (10 Hz) with column wheel and zero-reset architecture, offering COSC certification and precise fractional-second counting. The 19mm lug width integrates a tachymetric bezel, brushed steel case, anti-reflective sapphire crystal, transparent caseback, and 100m water resistance for daily wear.

Frequently asked questions

What is the lug width of the Zenith El Primero 03.2150.400/53.M2150?

The lug width is 19mm. This dimension is specific to this model and calculated to maintain visual balance with the 38mm case diameter. Do not confuse lug width (distance between case lugs) with strap thickness: 19mm is solely the width measurement.

Which strap is most suitable for the Zenith El Primero 03.2150.400/53.M2150?

Genuine alligator (Mississippi or Nile) is the most elegant choice, featuring fine and consistent grain that enhances the brushed steel case finish. For intensive daily wear, full-grain vegetable-tanned calf leather offers superior durability and develops a characteristic natural patina. Shell cordovan is ideal for maximum durability and slow ageing over time. Alternatively, a dark grey NATO strap provides a casual and practical approach.

How do I change the strap on my Zenith El Primero 03.2150.400/53.M2150?

The strap is changed using a spring bar removal tool. Locate the lugs (two lateral case spurs), insert the tool from below the lug to press the internal pin, then remove the strap. Repeat on the other lug. Insert the new strap by aligning the holes with the lugs, press downward until the pin clicks into place. If unsure, consult a professional watchmaker.

Can I use a third-party 19mm strap on my Zenith El Primero 03.2150.400/53.M2150?

Yes, any 19mm strap is mechanically compatible. However, it is advisable to choose artisanal-quality straps that respect thickness and visual proportions: excessively thin or thick straps may alter the model's aesthetics. Alligator or calf leather straps with hand-finished details are most coherent with the luxury character of the Zenith.

How long does a leather strap last on the Zenith El Primero 03.2150.400/53.M2150?

Durability depends on material and usage. Alligator lasts 3-5 years with daily wear on an average wrist. Full-grain calf leather develops natural creasing and maintains elasticity for 2-4 years. Shell cordovan is the most durable: it withstands 5-8 years of intensive use due to material density and resistance. Sun exposure, moisture and humid environments accelerate ageing. Atelier Casati Milano provides 18-month warranty on all custom 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