The series 725 combines refined, yellow-golden color carbon trebles and basses wound with Goldin-wire. Our Super-Carbon trebles deliver a much softer and warmer sound than conventional carbon strings. The wire of the wound bass strings is made of the gold colored metal alloy "Goldin", which is 100% nickel and cadmium free. The bass strings create a clear and brilliant sound. Rated by many professional guitarists as one of the best strings for classical guitar.