IIRC it is an acronym for "Unshielded Twisted Pair" a term used to define wire and cable used in the IT industry or in our case car stereo as to its shielding properties
I ended up going with some JL RCA cables, but I had to sell my system, so now I hvae no use for them. If anyone wants them, PM or e-mail me. I have the 4 channel and 2 channel sets, both 18ft.