Rare vent cover found!

Marilyn and I were at an estate sale when a friend asked us if we had seen the rare cast iron vent cover.  I had, but did not know what it was!  It looked like a an iron plate with a lot of holes.  He then showed us how the center would rotate for removal.  Then you could install the vent pipe through the hole.  It looked like it had never been used.  We immediately knew where it would fit into the mansion - the master bedroom!  There is a vent hole high above the fireplace and we had been searching for just the right cover.  There are hundreds of painted covers available, but we had not found just the right cover for this room.  Marilyn and I immediately did a google search to learn about this form of vent and found very little.  Quickly we searched for a company that might supply these vents so that we could determine how high to bid at the auction.  No luck for this search either.  I had to go to work, but Marilyn stayed and had her hand waving in the air like a young girl meeting her boyfriend at the train station.  Excitedly, she then text me with the news.  I know, it sounds like parents talking about their kid's making the honor roll.  Well, that is the way we feel.