Many camera manufactures have come out with models that make you wonder "what were they thinking?" Zeiss Ikon, with the politics of the merger of four major manufacturers had more than their share. This is but one.
Zeiss took the design of the Super Nettel, a folding 35mm camera with the focal plane shutter of the Contax and the rotating wedge rangefinder from the Super Ikonta line, and made it into an interchangeable lens rigid body camera. This essentially put it into the same market as the Contax II and III, although it was no match for features. It lacked the large combined viewfinder and rangefinder, and the self timer. Although you might tend to think of it as a stripped down Contax (much as the Leica came in models with fewer features for a lower price), it wasn't. Nothing, other than film cassettes and lens caps were interchangeable between the two. The Nettax had an odd mount with a lobe at about 11 o'clock containing the rangefinder window. The only lenses made for the Nettax were the standard 50/2.8 and 50/3.5 Tessars, and the 105/5.6 Triotar, very few of which were made.
The camera was finished in chrome, and was introduced in 1936, the same year as the new Contax II and III cameras, and the Super Nettel II. The camera sold poorly, and was discontinued in 1938. They are fairly uncommon today, and most have shutter problems.
Zeiss reused the name Nettax on a 6x6 folding camera, a deluxe version of the Nettar in 1955-57, which should not be confused with this camera.
With the lens removed
The 50/2.8 Tessar
Back of the mount
Back, showing the Contax-like shutter
The cap, same as supplied on the 50/2.8 and 50/3.5 Tessar lenses for the contax