I asked Pat Barkwell for help in identifying this little insulator. We all know Pat's good sense of humor and so I have to post a part of his reply...""Thet thar ees a LRI ! Dude that's sweeeeeeet ! The ground cable for a lightning rod ran thru that. It kept the dishcharged strike from burning down the house. """ Well, anyway, I guess the photos don't show but there are some milk streaks. A flake and some rough edges around the cable hole. The bracket seems to be cast zink or cast aluminum. The color is aqua blue. It is 2.5 inches high and 2 inches across.