STUSA Mainspring for Waltham Colonial A - 10s / 12s No. 2234 - Steel

STUSA Mainspring for Waltham Colonial A - 10s / 12s, 21J or better (not strong enough for lower jewel movements), Factory No. 2234, new envelope. 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.