Edizione Inalterabile is mentioned on the advertising card, with several "translations" underneath. A different advertising card from the Rome address has (in German, English and French but not Italian) "Artistic permanent photographs of all Italy - views - paintings sculptures- illustrated post cards - stereoscops. Trade mark Edizione Inalterabile. Photographic paper N.P.G." These are larger souvenir photographs but also include postcard versions.
Figurative CR cards which fall outside the Inalterabile range often also name NPG. The firm evidently had a close relationship with NPG beyond the supply of materials. It must have become the branch or associated partner company which NPG had in Milan, according to most online accounts of NPG. #
The series names for these cards appears to be Diffida; there are also Diffida cards with an ASC logo, which also have an NPG logo on the face.
A similar logo, a gear-wheel outline containing a monogram starting with C, was used by A Traldi of Milan (qv), this is presumably just a coincidence. In fact there is even a vaguely similar French logo for C. Jeangette (qv). names