/diy/ - Do It Yourself

What in unholy fucks name is this cunt of a connector called? It's on a 12v dc adapter for a Sony equipment, I thought maybe it was proprietary but a 24v adapter for a Samsung uses the same.
Don't have caliper at hand so I'm using a shitty ruler but max diameter is a little over 5mm, the barrel(?) is metal on the outside, the pin is recessed about 3mm and looks about .75mm, inside of the barrel is plastic. Internal diameter 3mm, plug length 10mm.
I need to extend it by 6ft but no matter where or how I look I can't find a right extension cord. All I'm finding are cords where the pin is in receptacle and i seriously couldn't find a technical name for it.