D'Addario EJ80 Phosphor Bronze Octave Mandolin Strings, Medium, 12-46 D'Addario's octave mandolin strings are designed for use with octave mandolins of various scales. The unwound strings are made from plain steel and the wound strings are phosphor bronze. String Gauges: Plain Steel .012/.012, Phosphor Bronze Wound .022/.022, .032/.032, .046/.046