Vintage metal one way exhaust valve for old dry sui hard hat diving helmet suit?

Description

We don't know much about this valve so buy it now and get a steal of a deal if you know what it is.  It is for sure a one way exhaust valve for a diving suit.  Is it for a hard hat suit or scuba suit?  We don't know.  It could be a rare Morse or Miller Dunn item or even John Date?  You tell us if you know.  We think it is new old stock and never before installed, but we don't really know.
This just in.....I have several people that say it is from an early unisuit and a few say it is from an eastern European diving dress.  Soooo still dont know for sure.