Pro-Arte, the world's most popular classical strings are D'Addario's premium classical guitar string sets. All Pro-Arte treble strings are sorted by a sophisticated computer-controlled laser machine which performs diameter and tension measurements, ensuring true-sounding, precise trebles in every set. Pro-Arte basses are wound using silver-plated copper on a multi-filament nylon core for consistent and warm, yet projecting tone. D'Addario offers a full range of classical guitar singles for all your replacement or customization needs. The perfect replacement string for the D'Addario EJ47 Pro-Arte 80/20 Normal Tension fourth string. Normal Tension. Perfect as a replacement string or for creating customized sets. Made in the U.S.A. for the highest quality and performance. String Gauge: .028