H. & W. Perrin Co. Mainspring for Eterna caliber 600 - Alloy

H. & W. Perrin Co LTD UB Mainspring for Eterna caliber 600 movements and likely others as well, alloy, new in envelope. See image for precise mainspring specifications. H. & W. Perrin is the largest supplier of horological materials in Canada. All UB (unbreakable) mainsprings are very new and are being sold at or below cost. Images do an adequate job of representing the item.