STRING SET FOR CLASSIC GUITAR D'Addario Classics EJ30 string set. Normal tension The EJ30 is a set of normal-tension classical guitar strings containing silver-plated twists and clear nylon trebles for a very precise intonation. D'Addario Classics strings are made of hardened nylon hardened by patented grinding techniques. The control of the roundness and dimension are unmatched, guaranteeing absolutely a perfect intonation. The rectified nylon strings are known for their warm timbre and light texture feel.