{"product_id":"marco-mainspring-3011-for-gruen-300-301-307-327-328-329-350-etc-steel","title":"Marco Mainspring 3011 for Gruen 300, 301, 307, 327, 328, 329, 350, etc. - Steel","description":"\u003cp\u003e\u003cstrong\u003eMarco \u003c\/strong\u003eMainspring 3011 for \u003cstrong\u003eGruen\u003c\/strong\u003e 103, 300, 301, 307, 327, 328, 329, 350, 520, 530, 531 caliber movements plus perhaps others, steel, new in envelope. See images for precise mainspring specifications. I specialize is 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":"C \u0026 E Marshall","offers":[{"title":"Default Title","offer_id":48982133997876,"sku":"PMS-CEM3011S-12","price":5.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0849\/3341\/1124\/files\/2025-12-2012.32.04.jpg?v=1766263063","url":"https:\/\/www.vintagetimeparts.com\/products\/marco-mainspring-3011-for-gruen-300-301-307-327-328-329-350-etc-steel","provider":"Vintage Time Parts","version":"1.0","type":"link"}