Longines unlocking yoke spring cal. 501 503 505 506 507 508 / part 2633

Longines 501 unlocking yoke spring / part 2633

Ressort de bascule de déclenchement

For all Longines following calibers : Longines 501 503 505 506 507 508 (not for L506 nor L507 based on modern ETA movement)

Neuf de stock / New old stock never used