In the animation below the perfectly symmetrical coupler used to build RD1 and RD2 is sliced at its two rhombic equators to reveal the composition of the rhombic face. In RD1, there are only Amods on the surface and no Bmod (green or red) BCE faces; hence, an allspace packing of RD1 would have no interspheric connectivity. Whereas, in an allspace packing of RD2, there are four channels of connectivity or contacts through the four BCE Bmod faces.