If you already know the composite GPM and want something more substantial, reference WW194003SS-0101 is the natural next step. The Marathon SSGPM trades fibreshell for a 36mm Parkerized steel case and swaps the automatic for a Swiss hand-wound movement, resulting in a field watch with a distinctly collector-grade feel.

Parkerizing is a protective phosphate finish used on military firearms and hardware, and on the Steel General Purpose Mechanical it gives the 316L case a flat, matte grey surface that will not glint in the sun. The extra two millimeters over the 34mm composite models, along with the 44mm lug-to-lug span, give it slightly more wrist presence while keeping vintage proportions. At just 11mm thick, it is also slimmer than its automatic siblings.

The movement is the Swiss Sellita SW210-1, a manual-wind caliber with 18 jewels and about 45 hours of reserve. Marathon pairs it with sapphire crystal, 5 ATM water resistance, a black dial with 12/24-hour scales and self-powered tritium on the markers and hands. A black one-piece nylon strap, 10 inches long, keeps the look utilitarian. For a collection built around genuine military makers, the SSGPM fills the steel, hand-wound slot neatly.

WW194003SS-0101 at a Glance

• Model: Marathon SSGPM (Steel General Purpose Mechanical)
• Case: Parkerized 316L steel, 36mm, 11mm high, 44mm L2L
• Caliber: Sellita SW210-1, manual winding, 18 jewels, ~45 hours
• Water resistant to 5 ATM
• Sapphire crystal, pressure crown
• Tritium gas tubes on hands and markers
• Black dial, 12/24-hour scales
• Black one-piece nylon strap, 10"

The steel, hand-wound answer for the serious field-watch collector.