1940s Birks/Eterna Challenger Military

This hand-wound "Birks Challenger" was manufactured by Eterna for the luxury Canadian retailer Henry Birks & Sons and marketed heavily to Canadian servicemen. Powered by Eterna’s workhorse Caliber 520 T, featuring early shock-protection geometry for enhanced durability in the field, it displays a high-contrast military dial with full Arabic numerals, a sub-seconds subdial at 6 o'clock, radium/lume-filled hands, and an inner 24-hour military track. The watch is housed in a rugged, solid stainless steel screw-back case stamped on the back with "Waterproof," "Antimagnetic," and "Shock Absorber."

Maker: Eterna (retail double-signed for Henry Birks & Sons) 
Model: Birks Challenger (Military / Field Dial)
Reference: Typically non-referenced on exterior dial; inner caseback stamped with Eterna production/case serials (e.g., 29x / 30x / 36x series runs)
Year of Production: ~1940–1948 (WWII era)
Case Dimensions: 34mm
Movement: Mechanical manual-wind (hand-wound)
Caliber: Eterna Caliber 520 T (15 to 17 Jewels, 12''', 18,000 bph, "T" suffix designated for early shock-absorber protection)
Power Reserve: ~38 hours
Bracelet/Strap: Leather
Lug Width: 18 mm
Original Box/Papers: Not included