Unmarked Mainspring for 12s South Bend Factory No. 55528 - Steel

Unmarked Maker Mainspring for 12s South Bend 1st model Pocket Watch, Factory No. 55528, steel. Measures Dennison 11 x 5½+ x 18½. I suspect this was an early Hammel, Riglander & Co mainspring as it resembles the ones I have from them used in Dollar watches. I specialize in hard to find watch parts and all watch parts are unconditionally guaranteed. Images do an adequate job of representing the item.