Quality strings since 1956; Steel core, metal alloy or fibre 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; A “Classic” chrome steel; string thickness/tension:; soft 0.74mm/16.3kp/35.8lbs; medium 0.75mm/17.9kp/39.4lbs; forte 0.76mm/18.5kp/40.7lbs;