D'Addario Pro Arte EJ45C, normal tension, is D'Addario's best selling "composite" set, preferred for its balance of bold, yet warm tone, comfortable feel and dynamic projection. Pro-Arte Composite strings feature an exclusive multifilament stranded core material which delivers a powerful, but warm tone which lasts 2-3 times longer than traditional classical strings. In addition to three traditional nylon treble strings, each set contains an optional monofilament Composite 3rd/G string, which provides greater projection and optimal balance between basses and trebles. All Pro-Arte treble strings are sorted by a sophisticated computer-controlled laser machine which performs diameter/tension measurements and quality checks, ensuring true sounding, precise trebles in every set.