The eyepieces consist of two converging lenses which, since the reproductions placed near their focal plane supply two distinct virtual images that appear very far away which, once the instrument has been focused, appear superimposed with no problem of convergence or adjustment.
The tubes of the binocular are black on the inside and ensure that each eye cannot see, even indirectly, the image seen by the other.
The stereoscope is accompanied by eighteen pairs of photographs of views, scenes and panoramas of which six, on transparent paper, coloured by hand on the back and quite well done, can be observed in transmitted light while the others require reflected light; of the latter, two views of Florence bearing the words: Giacomo Brogi - Firenze - Lung'Arno delle Grazie 15, and one view of Cagliari.