<p><span id="productDescription" class="cms-copy">Born from our greatest breakthrough in string innovation, XS Phosphor Bronze strings have the longest life of any D’Addario acoustic guitar string. The XS coating gives our warm, balanced phosphor bronze strings maximum life, with an uncommonly smooth feel. Made with a NY Steel core, phosphor bronze wrap wire, and Fusion Twist technology, XS coated acoustic guitar strings have incomparable break strength and tuning stability, in addition to their dramatically increased lifespan. This 13-56 Medium gauge set provides maximum volume and projection, with more tension and resistance.</span><br /><span id="subBrandDescription" class="cms-copy sub-brand-description"><span class="screen-sm-hidden"><br /></span>XS is breathing new life into coated strings. With its ultra-thin film coating on every wound string and a unique polymer treatment on the plain steels, XS offers our highest level of protection, for maximum life with an uncommonly smooth feel. XS also features NY Steel high carbon core and plain string wire, along with our exclusive Fusion Twist, for incomparable break strength and tuning stability. XS is the most innovative coated string ever created.</span></p>