.028 .032 .040 .028w .035w .044w These strings will stand the test of time with you and your playing. D'Addario XT Classical Guitar Strings offer an extended string life while maintaining the tone and feel of your favorite un-coated silver plated copper string. D'Addario XT Classical Guitar Strings utilize the proprietary composite basses and precisely intonation trebles of D'Addario's Pr-Arte strings. D'Addario XT Classical Guitar Strings deliver dynamic response and long-lasting performance. XT treated silver plated copper basses Pro-Arte Trebles