Gauges 28-32-40-29-35-43. EJ47 Pro-Arte guitar strings are D"Addario"s premium classical guitar strings. Treble strings are measured by a sophisticated computer-controlled laser which performs consistency and quality checks, insuring true-sounding strings in every set. Basses are made with 80/20 bronze wound on nylon. D"Addario is among world"s largest manufacturers of strings for musical instruments. Many top guitarists won"t play any other brand. Regardless of your playing style, D"Addario has a set of strings that"s right for your classical guitar.