What tape do they use to shell PCIe extension cables?

[1461748123]

As title, something like this:

I'm guessing those are aluminium or copper tape, but how did they get that matte black finish?
I wanna get some for my extension cable as well

 

[confusis]

http://www.polymerscience.com/products/p-shield-1374-black-conductive-tape/ ?