Original Apple DB15 to "13W3", 2m display cable for connecting the Apple Portrait Display to a standard DB15 Apple monitor port. This is the early version that only used 1 coaxial wire to carry the monochrome video signal.
When Apple first introduced the Portrait monochrome display in the late 1980's, they utilised 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.