Enneagonal duoprism

The enneagonal duoprism or edip, also known as the enneagonal-enneagonal duoprism, the 9 duoprism or the 9-9 duoprism, is a noble uniform duoprism that consists of 18 enneagonal prisms and 81 vertices. It is also the 18-8 gyrochoron. Together with its dual, it is the first in an infinite family of enneagonal dihedral swirlchora.

This polychoron can be subsymmetrically faceted into a triangular triswirlprism, although it cannot be made uniform.