Here's a nice example of one of these. I'm believing I removed this from a telegraph pole along a Southern Pacific spur line between Hillsboro and Roy, Oregon in 1968. Oddly, this line, which was abandoned and no longer in use, utilized three insulators on each cross arm and three wires attached. Weird! Anyway, add this one to your collection for $25 shipped. PayPal preferred. Thank you for looking!