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Omega · X-33 / Z-33

Strap for Speedmaster X-33 Marstimer Titanium / Black / Bracelet

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 Omega
Lug width20 mm
Case diameter45 mm
Reference318.90.45.79.01.003
FamilyX-33 / Z-33
MovementOmega caliber 5622 Additional 12 Hour Hand (adjustable), Additional 24 Hour Hand (adjustable), Hours, Minutes, Seconds | Date, Day, Month, Perpetual Calendar, Year Indicator | Chronograph, Countdown, Flyback | Alarm
CaseTitanium, Aluminium

Recommended spring bar

Spring bars Omega 20mm — 1.8mm diameter

Technical match for lug width and diameter · lug 20 mm · Ø 1.8 mm

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Straps for the X-33 / Z-33 318.90.45.79.01.003

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The X-33 / Z-33 318.90.45.79.01.003, seen from the bench

The Omega Speedmaster X-33 Marstimer (ref. 318.90.45.79.01.003) is a professional chronograph developed through a decade-long partnership between Omega and the European Space Agency, certified by NASA and ESA for use in microgravity and extreme environments. The 45 mm titanium and aluminum case houses the Omega caliber 5622 quartz movement, featuring dual time displays (12/24-hour), perpetual calendar, year indicator, and flyback chronograph function. The 20 mm lug width accommodates standard straps designed for this professional category of timepiece.

Frequently asked questions

What lug width does the Omega X-33 / Z-33 318.90.45.79.01.003 have?

The Omega X-33 / Z-33 318.90.45.79.01.003 has a lug width of 20 mm. This means that any compatible strap must be designed exactly for this width. Always verify by measuring directly between the two lugs of the case before ordering an aftermarket strap.

What is the best strap for the Omega X-33 / Z-33?

The best strap depends on usage: for daily elegance, cognac brown alligator or vegetable-tanned calf amplify sophistication; for technical-military character, a grey or black NATO strap echoes aerospace origins; for maximum functionality and durability, vulcanized rubber is unbeatable.

How do you change the strap on an Omega X-33 / Z-33?

The strap is changed using a spring bar removal tool or a very thin screwdriver. Position the tool in the grooves on the sides of the spring, apply gentle pressure to make it click, and the strap will detach. Reverse the procedure to install the new strap. If you are not experienced, entrust the task to a professional watchmaker.

Is there a truly compatible aftermarket strap for the 318.90.45.79.01.003?

Yes. MilanoStraps offers a complete collection of 20 mm straps for this model, crafted in leather (alligator, calf, shell cordovan) and technical materials. All are available with customizable length, initials, and stitching choice.

How long does a leather strap last on this model?

A fine leather strap (alligator or calf) typically lasts 3-5 years with moderate daily wear. Lifespan depends on exposure to water, sweat, direct sunlight, and cleaning frequency. MilanoStraps straps include an 18-month warranty against manufacturing defects.

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