The elongated pentagonal orthobirotunda is a convex equilateral orthobirotunda having regular pentagonal upper and lower rotundas arranged symmetrically with respect
to each other and separated by a vertical strip of squares. It is Johnson
solid .

The unit elongated pentagonal orthobirotunda has volume

where the first expression uses the basis of Conway et al. (1999). It can be dissected into the elongated
pentagonal gyrobirotunda, from which it differs only by relative rotation of
the top and bottom rotundas.

Conway, J. H.; Radin, C.; and Sadun, L. "On Angles Whose Squared Trigonometric Functions Are Rational." Discr. Computat. Geom.22,
321-332, 1999.Johnson, N. W. "Convex Polyhedra with Regular
Faces." Canad. J. Math.18, 169-200, 1966.