Carl Zeiss Sonnar T* 38mm f/2.8 Pancake Prime lens, Leica Uncoupled M39 Mount 
Tiny sharp full frame wide angle lens with an M39 mount.
The optics are clean with no issues and the focus and aperture move well.
It has been mounted onto an uncoupled M39 mount.
For full frame Leica film or any number of digital mirrorless cameras.
With rear cap.