H. & W. Perrin Co. Mainspring for Buser 20, Phenix 89, 93, 250, 253 - Steel

H. & W. Perrin Co Mainspring for Buser caliber 20, Phenix caliber 89, 93, 250, 253, Blancpain caliber 42, 47, 5U movements and perhaps even more still, steel, new in envelope. See images for precise mainspring specifications. I likely have several of these so the one you get may differ slightly from the images. H. & W. Perrin is the largest supplier of horological materials in Canada. Images do an adequate job of representing the item.