Up for sale is a vintage lens Tessar 2.8/50mm by Carl Zeiss. Unfortunately I don't know what kind of mount it has. Suggesting it is Exa bayonet. The lens is old, has got some dust pieces inside it. Glasses seem to be in good shape. It comes with 2 rings and box. One ring is an adapter bayonet-to-M39. One ring is an adapter M39-to-bayonet.
eBay