D'Addario EJ51 Pro-Arte Classical Guitar Strings with Polished Basses, Hard Tension Feature polished basses for reduced finger noise - ideal for recording Laser sorted black nylon treble strings for consistent, precise intonation Hard tension, a popular choice for its rich tone, increased resistance and strong projection Made in the U.S.A. for the highest quality and performance String Gauges: Trebles .0285, .0327, .0410 Basses .030, .036, .044