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)