I just got in from Italy this 15KV rated Richard Ginori 3 shell, unipart Porcelain Insulator. This insulator is fairly common and was used starting in the 1960's as a replacement for the green Weitschirm family versions. The green Weitschirm insulator dates from the 1930's either as an unmarked version or Verbano.

Both versions of this insulator were used on the Roma Viterbo Railroad line. This railroad was first put into service on April 29, 1894.

Again thanks to Nora for her great wealth of knowledge!