Thomastik-Infeld Plectrum Acoustic Guitar Strings are soft sounding and have low tension on the bottom end. The plain strings are made of brass coated steel. The wound strings have a silk inlay combined with a highly flexible steel core. The combination of lower overall tension, hybrid arrangement of flatwounds and silk inlays of these Thomastik-Infeld Plectrum Acoustic Guitar Strings produces a beautiful, almost classical tone, with the warmth of bronze and the easy playability of a fine set of jazz strings.