FT92 are very common telephone insulators in Italy but some of them are quite rarer than others. The Boral one is rare indeed but not a new discovery for Italian collectors! We already know a specimen found by our friend Davide Franchini in Emilia Romagna Region.
Update: Probably, as our friends from Abruzzo say, Boral was a patent used by Fidenza to compete against the Miva's monopoly. It did not have luck because Boral insulators or more in general Fidenza insulators for Italian State Telephones are quite rare.