I ran across this getting connectors for my Corvette and thought it rather unique, not to mention....well, just a little lazy when it comes to using a multi-meter. But it also makes a quick reference when an issue arises and you don't have that multi-meter.

Since the X308 is fickle when it comes to its electronics and the battery is the main culprit of issues when its not up to par, I thought it worth posting. Not to mention if you either just have to have that niche' thing no one else has or can't figure out what to get your gear head as a gift.

http://www.wiringproducts.com/4-port...-terminal.html
http://www.wiringproducts.com/4-port...-negative.html

From what I can gather from the lone pic, it appears its an allen wrench lug to clamp the wires down.

 

seems to be a solution in search of a problem

 

They're also pretty popular with the car audio scene - the "flashy" one, that is. Where everything has to have a voltage readout on it. And gives you the multiple connections for components off both terminals. Works better on a car that doesn't have the battery hidden though.

 

I was going to say, I had one of these setup on my other car when I first set up the sound system... I quickly ditched it though once I was able to repair the odd stock connector and get a crimped eyelet bolted onto the positive connector, and consolidate all the audio power to a single 0ga run.

For the XJR, I considered getting a cheap voltmeter that can plug into the lighter socket, maybe not the most precise but it could provide quick feedback on alt behavior.