The one I have is, i believe, Century interchangeable camera mount for Arri PL. Works with all Century interchangeable lens systems.
https://www.schneideroptics.com/ecommerce/CatalogItemDetail.aspx?CID=1106&IID=1259
This sells for about $420 and is now sold by www.schneideroptics.com
Mine that i want to trade is on the red felt.
What i need it the adapter that goes on the back of the Angeneuix 25-250 interchangeable PL Mount.
the one i need is on the white background.
I believe it is like this: http://www.ebay.com/itm/370830974198?euid=6bd856bd0a4a43658889cb449b1d16e9&bu=44536227626&cp=1&sojTags=bu=bu