FITRITE Clock Mainspring 4.73 x .28 mm x 575 for 8-Day Travel / Alarm

FITRITE Clock Mainspring, OPEN LOOP End, Dennison 38½ x 3/0½ x 23", for unspecified maker 8-day Travel / Alarm clocks made from the 1950's or later, steel. See images for further details. Was originally sold as part of assortment No. 2880 for clockmakers. I specialize is hard to find watch & clock parts and all parts are unconditionally guaranteed. Images do a pretty good job of representing the item.