Omega® Crown (Dustproof), steel, case numbers are unknown
Omega® Steel Dustproof Crown, diameter 5.30 mm, tap 0.90. Case numbers are unknown.
* 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.