Omega® Crown Nut, calibres: 640, steel
steel nut (slotted) for Omega® caliber 640 back wind, diameter of nut is 3.80 mm
* H. & W. Perrin Company Limited is independent of and not affiliated with or sponsored by Omega®. Omega® warranty does not apply to parts supplied by H. & W. Perrin Company Limited. Using generic parts may devalue your watch.