Quite rare (only about 169 lenses produced) Carl Zeiss lens (front ring engraved 'Oberkochen OPTON S-Pl 1:2.8 f=100mm') made to highest possible technical and optical standards, heavy brass mount, non-focusing barrel without aperture in uncommon 40mm screw mount, front element diameter c.37mm, rear element diameter c.27mm, total height c.90mm, covering 6x6cm film format, clean optics.

There is a small defect near the glass edge, but it should not affect image quality.