GHS Progressives are nickel roundwounds. Most noteworthy thing about them IME is that they are one of the very few four-string sets to feature an exposed-core "E" string.
I tried 'em once - and soon found that I had major problems with intonation. While I was able to intonate the "E" string by moving the bridge saddle way, way back, each of the other three strings, being conventional wound strings, had an intonation point much closer to the neck end of the instrument.
At the end of the day, my bridge simply didn't have enough adjustability to accommodate both types of string in the same set. I chucked 'em out, moved on to another make & model, and haven't looked back since...
MM
