D'Addario XT13/56 Phosphor Bronze Acoustic Guitar Strings .013-.056Never Fade Away D'Addario XT Strings last 4 times longer than traditional uncoated strings without sacrificing the tone or feel that players know and love. Extended Life Natural Feel Stand the test of time with strings that endure. D'Addario XT strings combine high carbon steel cores with an extended lifespan treatment on every string in the set, giving you enhanced break resistance, pitch stability, and long lasting performance all while preserving