{"product_id":"swartchild-black-shield-clock-open-loop-mainspring-4-80-x-41mm-x-54-ms-253","title":"Swartchild Black Shield Clock OPEN LOOP Mainspring 4.80 x .41mm x 54\" - MS-253","description":"\u003cp\u003e\u003cstrong\u003eSwartchild \u0026amp; Co \u003c\/strong\u003eClock Mainspring, OPEN LOOP End, Dennison 3\/16 x .016 x 54, P\/N MS-253 (80-504) from the 1950's or later, steel, new in envelope. See images for further details. My guess is this is for an 8-Day clock, based on the length of the mainspring, although I don't know which one. I'll also point out that these need some serious cleaning before use. I specialize in hard to find watch \u0026amp; clock parts and all parts are unconditionally guaranteed. Images do a pretty good job of representing the item\u003c\/p\u003e","brand":"Swartchild","offers":[{"title":"Default Title","offer_id":48615916273972,"sku":"CMS-SWRDMS253S-06","price":6.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0849\/3341\/1124\/files\/2025-06-0616.52.32.jpg?v=1749254236","url":"https:\/\/www.vintagetimeparts.com\/products\/swartchild-black-shield-clock-open-loop-mainspring-4-80-x-41mm-x-54-ms-253","provider":"Vintage Time Parts","version":"1.0","type":"link"}