Been using them for 15 years as my strings of choice on all my guitars. Never had any problems - they do not rust, tarnish, go dead, break or lose intonation. Very good tuning stability, slick, fast, great harmonics. I clean them with Dunlop 65 string cleaner after each use, and my frets as well with a cloth and fretboard. They sound fresh for months like this, and everything is shiny and slick and fast. Used them also in Eb or D tuning. They sound great for those as well.