Lot of 2 Hamilton Dynavar Mainspring for 20/0 & 21/0s Nos. 717531 & 717532- Alloy

Lot of 2 Hamilton Factory Dynavar Mainspring for 20/0 & 21/0s Movements, Catalog Nos. 717531 & 717532, alloy, new in envelope. Made for Grades 995, 995A, 997 & 721, and perhaps others. See image for precise characteristics. Images do a pretty good job of representing the item.