D'Addario XS Acoustic Phosphor Bronze combines the most popular acoustic alloy with our most advanced string coating technology, resulting in clear tone, smooth feel, and superior tuning stability — all with the longest possible string life. 

XS is breathing new life into coated strings. With its ultra-thin film coating on every wound string and unique polymer treatment on the plain steels, XS offers the highest level of protection for maximum life with an uncommonly smooth feel. XS is the most innovative string ever created.