Tritium or MaraGlo? Reference WW194009BK-0001 is the Marathon General Purpose Quartz for buyers who choose the second: a 34mm Swiss quartz field watch whose markers and hands are coated in Marathon's own light-charged MaraGlo lume, framed by a black dial with the "U.S. Government" marking.

The difference between the two is worth understanding. Tritium tubes glow on their own, continuously, for many years. MaraGlo is photoluminescent: it absorbs sunlight or artificial light and then releases it, glowing brightly for several hours after a charge. For daily wear, where the watch sees light most of the day, MaraGlo delivers a strong glow at night, and it avoids the radioactive gas tubes entirely, which some buyers and some workplaces prefer. Everything else about the GPQ remains true to its military roots.

The case is black composite fibreshell, 34mm wide and a slim 11mm thick, built to MIL-PRF-46374G, Type I, Class 1. A Swiss ETA F06 high-torque quartz movement keeps time and powers the hands. Sapphire crystal, a pressure crown, 12- and 24-hour scales and government markings on the caseback complete the package, on a black one-piece nylon strap.

Marathon GPQ MaraGlo WW194009BK-0001 Specifications

• Reference: WW194009BK-0001, General Purpose Quartz with MaraGlo
• Case: 34mm black fibreshell composite, 11mm thick
• Movement: Swiss ETA F06 high-torque quartz
• Water resistance: 3 ATM
• Crystal: sapphire; pressure crown
• Lume: MaraGlo photoluminescent on markers and hands (no tritium)
• Dial: black, U.S. Government marked, 12/24-hour scales
• Strap: black one-piece nylon

Charge it with daylight, read it all evening.