{"product_id":"samson-mainspring-no-4039-for-eterna-616-1057-eta-761-879-1040-1201-1212-steel","title":"Samson Mainspring No. 4039 for Eterna 616, 1057, ETA 761, 879, 1040, 1201, 1212 - Steel","description":"\u003cp\u003e\u003cstrong\u003eSamson \u003c\/strong\u003eNo. 4039 steel mainspring for Chezard 40, Cortebert 686, Eterna 616, 1057, ETA 761, 879, 1040, 1201, 1212 caliber movements and perhaps others as well, new in envelope. See images for all supported movements and precise mainspring specifications. I likely have several of these so the one you get may differ slightly from the images. I specialize in hard to find watch parts so I usually have whatever you might need and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.\u003c\/p\u003e","brand":"Samson","offers":[{"title":"Default Title","offer_id":49310700634420,"sku":"PMS-SAM4039S-10","price":5.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0849\/3341\/1124\/files\/2026-10-0413.18.59.jpg?v=1791145426","url":"https:\/\/www.vintagetimeparts.com\/products\/samson-mainspring-no-4039-for-eterna-616-1057-eta-761-879-1040-1201-1212-steel","provider":"Vintage Time Parts","version":"1.0","type":"link"}