I am in need of a retaining ring for a Schneider Tele Xenar 1:5.5/360
it is sitting in a compound shutter with a 58mm /60mm thread
(not to shore of the size)it will need to be about 10mm wide to cover
the gap between the shutter and the lens bourd,which is a copal 3.
If anyone knows the exact size or has one it would be a great help.

Many Thanks Stuart.