USR Mainspring No. 552 for 12s Howard Pocket Watch - Steel

USR Mainspring for 12s Howard Pocket Watches, Factory No. 552, steel, new in replacement envelope. Original envelopes had disintegrated, which is not unusual for USR envelopes. I likely have several of these so the one you get may differ slightly from the images. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do a pretty good job of representing the item.