Quality strings since 1956; Steel core, metal alloy or fiber winding; Warm, brilliant sound and durability; The “Classic” series standard strings; The A+D strings of the “Special” series are 0.01 mm thicker; The “Superior” strings are 0.02 mm thicker than “Special”; The “Silver Sound” G strings with flexible steel core and silver winding; C “Silver Sound” silver; string thickness soft 1.68mm, medium 1.69mm, forte 1.70mm;