Pro-Arte strings are the world's best selling and D'Addario's premium classical guitar strings. All Pro-Arte treble strings are sorted by a sophisticated computer-controlled laser machine which performs diameter/tension measurements and quality checks, insuring true sounding, precise trebles in every set. Pro-Arte basses are wound using silverplated copper on a multi-filament nylon core.   Gauges: .0285; .0327; .0410; .030; .036; .044