Great strings. I didn't think that NYXL's could be improved, but these are the same thing, with a protective coating, for even longer life. I was getting over double the operating life of the standard XL's when I switched to NYXL's (although I clean my strings after every gig/rehearsal). With the coating these XS's have, I don't need to be quite as meticulous with my string cleaning regime, and they feel & sound great (as you would expect from D'addario). They are expensive, but they do last much longer, so you get your moneys worth.