Check the listing for details. La Bella Guitar Strings 5 Sets Classical Professional Series 413P - Studio. Condition: New, Made in United States. Listed at 95.98 USD. 5-Packs! Developed in the 1970s, the Professional Series product line were the first classical guitar and lute sets to be offered in a wide variety of gauges. They have been acclaimed by concert guitarists, lutenists and prominent teachers and even used by such great luthiers as Del Pilar, Rubio, Papazian, Van Lennep and Gurian. The Professional Series have been the preferred strings by a whole generation of great artists including: Laurindo Almeida, Julian Bream, Mario Escudero, Maria Luisa Anido, Sabicas & Rey de la Torre. The Professional Series strings are still the standard for excellence expected by all serious guitarists. No single set of strings can possibly bring out the finest qualities of every type of guitar or best suit the varied technique and styles of every guitarist.