This is a beautiful specimen of the Richard-Ginori's production from about 1910 to 1919 circa. We can find it on a catalogue of these years with the model number N#1489. It was rated for a line voltage of 75.000 V and its net weight is 25 kilos.
These big insulators were quickly replaced with some other more modern ones because of they were very defective due to the cement dilatation. For this reason they are nowdays quite rare to find.
This specimen has two big N#24 stamped on the shells: probably they were the batch's number..