Yeah it's only the lower strings which are cobalt wound, the top 3 are steel! They're not RPS (I don't recall seeing them being RPS when I was putting them in anyways) Although they do feel a little more slinky on the top than usual, must just be in my head
So far, I LOVE 'em! Just wish they did singles, I use a 62 for my low B and I gotta go nickel for it, inconsistency is something I'm a little anal about!