APAS-89 androgynous docking unit.
original drawing: NASA, vectorization: <a href="//commons.wikimedia.org/wiki/User:Chabacano" class="mw-redirect" title="User:Chabacano">Chabacano</a>
<a rel="nofollow" class="external free" href="http://ston.jsc.nasa.gov/collections/TRS/_techrep/RP1357.pdf">http://ston.jsc.nasa.gov/collections/TRS/_techrep/RP1357.pdf</a> vectorized