Super Angulon 21mm f4. Code SUMOM, later 11002K.
Serial number in the 1.67 million range, manufactured in 1959.
A Leitz-branded lens, but produced by Schneider as an ultra-wide-angle design. There are also Super Angulon lenses carrying Schneider serial numbers, though those are quite rare and considered collector items.
Optical construction is 4 groups and 9 elements. Although this is a Leica M-mount lens, removing the set screws and taking off the coupling ring allows it to be used on Leica screw-mount bodies as well. The minimum focusing distance is 0.4 m, with rangefinder coupling from 1 m.
Paired with the original IWKOO hood, the combination looks especially stylish. On digital Leica M bodies except the M11, please note that color shifts will appear toward the edges.

The front edge of the barrel and the aperture ring show a fair number of small marks, but for an SA 21mm f4, which is often found heavily used, this one has a rather clean appearance.
Fully overhauled in November 2025. The aperture and focusing helicoid operate smoothly, and rangefinder coupling is spot on.
Both the front and rear elements show very faint cleaning marks, and the front element has slight coating wear, but none of these affect actual photography. Considering how frequently Super-Angulons suffer from haze, the glass on this example is unusually clean. Test shots also produced very good results.
Comes with an original front cap. The rear cap is a third-party replacement.
A great choice for practical use.