Trying to stop over bidding for this:
I contacted the seller & they said it is a Collinear Series III #5.
Not that a Collinear is a bad lens but certainly a different beast. Not to mention the extra $ you may have bid for the Portrait Euryscope.
The seller added a tiny bit buried at the bottom of the listing that says it's a Collinear series III #5
The title (still present) is just so misleading. Like the guy that sold the series IV as "PORTRAIT" Euryscope.for I believe around $1800 WOW If you don't know better you can take a bath.