Ernie Ball Earthwood 80/20 Bronze Acoustic Guitar Strings Are Made From 80% Copper, 20% Zinc Wire Wrapped Around Hex Shaped Brass Plated Steel Core Wire. These Acoustic Guitar Strings Provide A Crisp, Ringing Sound With Pleasing Overtones. .011 .011, .015 .015, .024W .010, .030 .014, .042 .022W, .052 .028.