Original Apple "13W3" to "13W3", 6 foot display cable for Apple Two-Page & Portrait Displays. This is the earliest version that only used 1 coaxial wire to carry the monochrome video signal.
When Apple first introduced the large Two-Page and Portrait monochrome displays in the late 1980's, this cable was used to connect to the video card in the Macintosh which contained one coaxial wire presented as a coaxial connector alongside the standard pins. Although Apple later standardised on a 3 coax type, ("13W3" meaning 13 wires, 3 of which are coaxial), this earliest version only has 1 coaxial wire but is still referred to as "13W3" ("13W1" was already used for another cable type).
Please check that both your monitor and video card match the layout shown in the photos.