1.CORROSIONRESISTANT, EXTENDED LIFE XS Phosphor Bronze strings have the longest life of any D'Addario acoustic string, with no fraying, peeling, or tonal dampening, thanks to the ultrathin XS film coating. 2.WARM, BALANCED TONE Phosphor Bronze wrap wire provides triedandtrue D'Addario acoustic tone, with beautiful balance and warmth suitable for all musical genres. 3.STAYS IN TUNE, STRONGER STRING With a NY Steel core and Fusion Twist technology, XS Phosphor Bronze greater break strength and unmatched tuning stabilitystaying in tune 131% better than standard acoustic strings. 4.EARN REWARD POINTS XS Phosphor Bronze sets come with a code on the recyclable, resealable VCI bag, which you can register to earn Players Circle points.