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 .010, .014 .020, .028, .040, .050. Features: Made with an 80/20 bronze alloy wrap with a layer of silk between the wrap and steel core Silk helps produce a more mellow sound Makes the string feel more comfortable while reducing finger noise