PM ONYX Steel Mainspring #78 for Font caliber 175, 176, Benrus caliber AR, AT

PM Mainspring No. 78 for Font caliber 175, 176 & Benrus caliber AR, AT movements plus perhaps others as well, ONYX steel, new in envelope. See images for further data and precise mainspring specifications. I specialize in hard to find watch parts so I usually have whatever you might need and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.