It's a plastic ring Don. It has two small wires sticking out of it. You pass the hot AC power wire through the hole. Jab! So easy to install.
Then connect a teeny pair of wires (like 18 gauge speaker wire) to the two little current transformer wires (polarity doesn't matter here). The speaker wire then gets run to the meter and attach to two little screw-down contacts on the rear side. The AC power wires to the meter and run separate. What they do is solely provide power to the meter and a voltage reference point that the meter will show digitally.
These things are so easy to connect it isn't funny. I would however strongly recommend putting a 1/2 ampere glass fuse in line with the power lead.