Unitas mainspring 510 520 521 530 531 532 / MST 373

1 mainspring / Ressort de barillet / Zugfeder (1 piece)

New old stock / neuf de stock

Same mainspring for following calibers :

Unitas 510 520 521 530 531 532 and MST 373

Le prix est pour 1 ressort / The price is for 1 mainspring

Livraison sous film neutre / Shipping in neutral zip bag (the last one will be shipped with the original Usibel envelope)