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;C "Classic" Chrome Steel ;String gauges/tensions;dolce 1.70mm/13.7kp/30.1lbs;medium 1.71mm/13.8kp/30.3lbs;forte 1.72mm/14.0kp/31.0lbs;