A dos-a-dos binding is two books bound in reverse and separately yet still in one structure.
Other than being unusual outside of the 17th century, these beautiful bindings also feature:
Size - 95 x 150 mm, 3 3/4 x 6 inches
Supplied in its own bespoke box which has been covered in hand printed paper.
This is one of six and the only one made with this design of cover.