EJ45, normal tension, is D'Addario's best-selling classical set, preferred for its balance of rich tone, comfortable feel and dynamic projection. All Pro-Arte treble strings are computer controlled by an X-Y laser micrometer 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.