Watch-Craft Mainspring 4177W – 1.45 x 0.09 x 10¼" – Dennison 5½ / 12 – USA NOS. & E. Marshall Co., USA. Part No: 4177W. GenuineWatch-Craft 4177W mainspring fromC. Ideal for restoring mid-century wristwatches requiring this size and strength mainspring.
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