Kobalux / Avenon Super Wide 21mm F 2.8 lens was made by Y.K. Optical company from Yokohama in Japan. The lens was sold under several different names. In Japan it was called Avenon, in North America usually Kobalux, and it seems that it was also sold in United Kongdom under the name Pasoptik and possibly also under other names.
Y.K. Optical also produced 21mm viewfinder for the lens. Sometimes the viewfinder was included with the lens and sometimes it was not. At least in Japan, the Millennium Edition was sold without the viewfinder, though the lens always came with a small metal hood.
When mounted on a camera, the lens protrudes deeply into the camera body. Because of this, it cannot be mounted on some cameras, notably on Canon series V cameras, Canon series VI cameras (Canon P, etc.), and Canon 7 4. On these late Canon Leica Screw Mount bodies the lens would hit the camera's internal light shield.