If you have an Omega Centenary (either version, 28,10 or 30,10 movements), then you need this:
https://www.ebay.com/itm/394677479440
There is a member here who had some reproduced inserts made some years ago. A little birdy told me he might have one left.
gatorcpa
Another cheap steel Geneve in decent shape, this time no-date and non-luminous, last one went for $265 so these can be great value entry level pieces or first time watch buyers or as gifts. This one goes off in 4 hours, at $220 so far