Does anyone out there have an idea what this might be? It's well constructed and made from solid brass. I'm guessing it's a tool for clamping two cables together. One side has MAIN and the other has TAP cast into it. Received this response from Ron Jenkins....many thanks to Ron. it is what's called a hot line clamp, the tap or jumper is connected to the side connection then the ringed portion is grabbed with a grip all clamp hot stick so it can be attached to the main line high voltage only 7500 volts or more.