Friend of mine was asking me what this green porcelain item might be. All I know is that is porcelain, is green and it comes from Italy. Doesn't look like a "normal" insulator, as there is no wire groove present. Update: Hint: Siemens-Bock Railroad Insulator, rated 3KV This is one part of three used in the assembly. A good photo of one of these in use is located in "Foreign Insulators" here: [id=165237286]