Famous for first-class strings since 1956;Steel core string wound with thin filaments of pure or alloyed metal;Warm, brilliant tone and long life;"Classic" Series - standard strings;"Special" Series has 0.01 mm thicker A+D strings;"Superior" Series is 0.02 mm thicker than "Special";"Silver Sound" Series has G and C strings made of a highly flexible steel core with a top coil of pure silver;D "Classic" Chrome steel;String gauge/tension: ;dolce 0.97mm/13.6kp/29.9lbs;medium 0.98mm/14.0kp/30.8lbs;forte 0.99mm/14.1kp/31.0lbs;