The example is one of a big series showing figures in period costume against a dark background, illustrated by Colombo. Thee are quite thick cards with a textured surface and deckled edges, typical postal dates late 1920s. The stamp box is of the same design as that used in the GAM/GMA cards where Colombo also appears extensively, and Clou seems to be just a series name with the publisher Guarneri.
Clou means nail in French but in Italian it means highlight, of greatest interest.
