s it just a tester or is it something that remains attached to the cord the whole time and the car plugs in through it?

No, it's... imagine if you took a lamp cord, cut the wire flush with the plug. The plug would then be about the size and general appearance of the G.E. glow light. It's just a tiny neon light built onto a 110 vac plug, you just plug it into an outlet (or in my case, one of the sides of a cube tap on the end of an extension cord) and it sits there and glows happily for a few years before it wears out.

I do know that you can get extension cords that have a light built into them

Yes, I have one of those that I keep in the car when I have to plug in someplace other than at work. At work, I have a semi-permanently installed extension cord that stays attached to the building, with a cube tap on it. Unfortunately, it does not have the built-in indicator.

If I can't come up with one of the neat little G.E. lights, I'll just spend a couple of bucks and buy a cheap night light. It will use about 20 times the electricity (10 watts vs 1/2 watt) which means it will cost my employer the better part of 17 cents a week (figuring 10 cents/KWH). When you consider that they are running three 50,000 watt transmitters and one 25,000 watt transmitter 24 hours a day, I guess I can slip my 10 watt night light in under the radar...

Big problem, though, is bulb life. That night light bulb won't run four or five years like the little glow lights.

tanstaafl.