This Voigtländer/Cosina 4.0/25mm might be a unique lens. Basically it is a Snapshot-Skopar 4.0/25mm with different inscriptions. The brand name "Voigtländer" is nowhere to be seen on this lens. The lens and the lens cap have the inscription "Cosina". The Viewfinder has also the inscription "Cosina".
It comes with the adapter Leica screw mount to Leica M in the Snapshot Skopar box.
I bought this item from a former executive manager who at the time was involved in strategic matters in the Voigtländer company.
The collection consists of some 20 Voigtländer rangefinder cameras and some 35 Voigtländer and Zeiss lenses. All items are unused and new. Stored away during the last 15 to 20 years in a climatized environment.