Square-heptagrammic duoprism

{{Infobox polytope The square-heptagrammic duoprism, also known as sashedip or the 4-7/2 duoprism, is a uniform duoprism that consists of 7 cubes and 4 heptagrammic prisms, with 2 of each at each vertex.
 * dim=4
 * type=Uniform
 * obsa=Sashedip
 * coxeter=x4o x7/2o ({{CDD|node_1|4|node|2|node_1|7|rat|2x|node}})
 * symmetry=BC{{sub|2}}×I{{sub|2}}(7), order 112
 * army=Semi-uniform squahedip
 * reg=Sashedip
 * img=4-7-2 duoprism.png
 * off=auto
 * verf=Digonal disphenoid, 2cos(2π/7) (base 1) and $\sqrt{2}$ (base 2 and sides)
 * cells=7 cubes, 4 heptagrammic prisms
 * faces=7+28 squares, 4 heptagrams
 * edges=28+28
 * vertices=28
 * circum=$$\\frac{\sqrt{2+\frac1{\sin^2\frac{2\pi}7}}{2} ≈ 0.95341$$
 * dich=Ship–7/2–ship: 90°
 * dich2=Cube–4–ship: 90°
 * dich3=Cube–4–cube: $$\frac{3\pi}{7} ≈ 77.14286°$$
 * hypervolume=$$\frac7{4\tan\frac{2\pi}7} ≈ 1.39558$$
 * den=2
 * dual=Square-heptagrammic duotegum
 * conjugate=Square-heptagonal duoprism, Square-great heptagrammic duoprism
 * conv=No
 * orientable=Yes
 * nat=Tame
 * height=1
 * pieces=18
 * euler=0
 * loc=12}}

The name can also refer to the square-great heptagrammic duoprism.

Vertex coordinates
The coordinates of a square-heptagrammic duoprism, centered at the origin and with edge length 2sin(2π/7), are given by: where j = 2, 4, 6.
 * $$\left(±\sin\frac{2\pi}7,\,±\sin\frac{2\pi}7,\,1,\,0\right),$$
 * $$\left(±\sin\frac{2\pi}7,\,±\sin\frac{2\pi}7,\,\cos\left(\frac{j\pi}7\right),\,±\sin\left(\frac{j\pi}7\right)\right),$$

Representations
A square-heptagrammic duoprism has the following Coxeter diagrams:
 * x4o x7/2o (full symmetry)
 * x x x7/2o (I2(7)×I×I symmetry, heptagrammic prismatic prism)