Ernie Ball Earthwood 80/20 Bronze Acoustic Guitar Strings are made from 80 percent copper, 20 percent zinc wire wrapped around a hex shaped brass plated steel core wire. These acoustic guitar strings provide a crisp, ringing sound with pleasing overtones. Gauges: 0.011, 0.015, 0.022w, 0.030, 0.042, 0.052. Features: Made from 80 percent copper, 20 percent zinc wire wrapped around hex shaped brass plated steel core wire Provides a crisp, ringing sound with pleasing overtones Gauges: 0.011, 0.015, 0.022w, 0.030, 0.042, 0.052