Lovely little Summar 50mm f2 lens for sale with the old screw mount attachment which can be adapted to M cameras easily. 
 
This example has just had the front elements cleaned out so produces very sharp images, but still provides the characteristic Leica glow desired in lenses of this era. 
 
Aperture blades move freely and have no contaminants, and elements on the whole are free from dust/haze/fungus, though it does seem that the rear element has some dust inside which bears no effect on the final image.
 
Focusing is smooth and the infinity lock works well.
 
Included is just the lens itself, no adapter.