D'Addario EJ 80/20 Bronze Wound Acoustic Guitar Strings - 80/20 Bronze, commonly referred to as brass, is the original acoustic string alloy selected by John D'Addario Sr. and John D'Angelico in the 1930s. 80/20 Bronze strings are popular for recording due to their crisp, bold, and projecting tone and appeal to many traditionalists for their historical significance.