Fortis Cosmonaut Official Cosmonauts Chronograph Monolith

Reference 638.18.31

About this watch

The Fortis 638.18.31 is a robust tool that combines functionality, style, and a sprinkle of space adventure. This Swiss brand has carved out a niche for itself in the universe of aviation and space watches, so it’s no surprise that they’ve been the official timekeeper for astronauts. The watch features a sleek black PVD coating, Arabic numeral indexes, and stick hands ensuring readability. It's powered by the ETA caliber 7750, an automatic movement renowned for its reliability and precision. With a water resistance of 200 meters, this watch is more than capable of handling aquatic adventures. Its closed back adds a touch of mystery to the watch, allowing the external beauty to shine without revealing too much inside. The Fortis 638.18.31 features a lug width of 20 mm, making it versatile enough for both adventurous outings and formal occasions.
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Key Features

  • Automatic ETA movement with 25 jewels and 42-hour power reserve
  • 200m water resistance for aquatic adventures
  • Rotating bezel with 0-60 scale for tracking elapsed time underwater
  • Black PVD coating for a sleek, modern look
  • Arabic numeral indexes and stick hands for readability
  • Robust and durable design for everyday wear

Specifications

Brand
Fortis
Family
Cosmonaut
Model
Official Cosmonauts Chronograph Monolith
Reference
638.18.31
Movement
7750
Movement Features
  • Hours, Minutes, Small Seconds
  • Date, Day
  • Chronograph
Case
Stainless Steel 42mm
Dial Color
Black
Crystal
Sapphire
Water Resistance
200

Current Listings

FORTIS _____ B42 Mars 500 ORANGE _____ ** Limited Edition ** _____ 647.28.13.L.13 ___ B 42 watch Cosmonaut Marinemaster

FORTIS _____ B42 Mars 500 ORANGE _____ ** Limited Edition ** _____ 647.28.13.L.13 ___ B 42 watch Cosmonaut Marinemaster

Fortis - 647.28.13.L.13 · $1,199.001
A Fortis B42 Mars 500 watch with an orange color scheme and incredible lume, coming with a complete package including inner and outer box, instruction, patch, and warranty card.

  • Condition: Gently used, 93%
  • Case size: 42mm
  • Movement: B42
  • Water resistance: 500m
Posted at
Apr 21, 2025, 10:28 AM
Active
$999 _____ FORTIS _____ B42 Mars 500 ORANGE _____ ** Limited Edition ** _____ 647.28.13.L.13 ___ B 42 watch Cosmonaut Marinemaster

$999 _____ FORTIS _____ B42 Mars 500 ORANGE _____ ** Limited Edition ** _____ 647.28.13.L.13 ___ B 42 watch Cosmonaut Marinemaster

Fortis - B42 Mars 500 · $999.01
This Fortis B42 Mars 500 is a limited edition watch with an orange color and incredible lume. It comes with a complete package, including inner and outer box, instruction, Mars 500 patch, and Limited warranty card.

  • Condition: 93% gently used condition
  • Case diameter: 42mm
  • Strap type: leather
Posted at
Apr 21, 2025, 10:28 AM
Active