{"product_id":"1940s-birks-eterna-challenger-military","title":"1940s Birks\/Eterna Challenger Military","description":"\u003cp\u003eThis hand-wound \"Birks Challenger\" was manufactured by Eterna for the luxury Canadian retailer Henry Birks \u0026amp; 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.\"\u003c\/p\u003e\n\u003cp\u003eMaker: Eterna \u003cem\u003e(retail double-signed for Henry Birks \u0026amp; Sons) \u003c\/em\u003e\u003cbr\u003eModel: Birks Challenger (Military \/ Field Dial) \u003cbr\u003eReference: Typically non-referenced on exterior dial; inner caseback stamped with Eterna production\/case serials (e.g., 29x \/ 30x \/ 36x series runs) \u003cbr\u003eYear of Production: ~1940–1948 (WWII era)\u003cbr\u003eCase Dimensions: 34mm \u003cbr\u003eMovement: Mechanical manual-wind (hand-wound) \u003cbr\u003eCaliber: Eterna Caliber 520 T (15 to 17 Jewels, 12''', 18,000 bph, \"T\" suffix designated for early shock-absorber protection) \u003cbr\u003ePower Reserve: ~38 hours \u003cbr\u003eBracelet\/Strap: Leather \u003cbr\u003eLug Width: 18 mm \u003cbr\u003eOriginal Box\/Papers: Not included \u003cbr\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Vintage","offers":[{"title":"Default Title","offer_id":48514417492186,"sku":null,"price":1475.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1579\/8059\/files\/eterna-birks.jpg?v=1790700789","url":"https:\/\/clarkstreetmercantile.com\/products\/1940s-birks-eterna-challenger-military","provider":"Clark Street Mercantile","version":"1.0","type":"link"}