After the smaller "A" series and before the "A3P" came out, Spitz developed a planetarium for a larger dome that should compete with the Zeiss. It still uses pin hole projection for most of the stars which saves both money and weight. This projector is most unique in its mounting as only thin aircraft cable are used allowing the machine to appear to float "weightless" in the planetarium hall. The cables are attached in an "X" design and connected to the East-West- axis of the machine. The four cables that go up could have been a problem as they would get in the way of star projection. Since very few stars would be blocked at any one time this probably went unnoticed by the audience. Only three of these projectors were ever built.