D'Addario EJ46 Pro-Arte Hard Tension Classical Guitar Strings are manufactured by the World's best selling brand of guitar strings. D'Addario EJ46 Pro-Arte treble guitar strings are built and sorted by a hi-tech computer which checks diameter/tension and quality, ensuring that you get true sounding, precise trebles in every set. EJ46 classical bass strings are wound using silver-plated copper on a multi-filament nylon core for consistent, warm-yet-projecting tone.