I really like these strings for fretted or fretless basses, except that the B string (.130) that comes in the 5 string set seems really dead and dull...I contacted D'Addario and they sent me a single B string, as well as a new full 5 string set. Well, I put the single B on and it was nice...obviously not as bright as a roundwound, but bright and lively enough for me, and slappable. Then i put the new 5 string set on out of the package, and that B sucked. Now, D'Addario had actually sent me two single B strings because the first one took awhile to get here. I put the second one on, and again, bright and nice. It seems that the B's that come by themselves are made differently in some way from the B's that come in the 5 string set. The conclusion for me is to buy a 4 string set and the B seperately, which is a bit more expensive. I haven't contacted D'Addario yet, but I will. Anyone else notice this or have any other info?