Made from 80 percent copper, 20 percent zinc wire wrapped around hex shaped brass plated high carbon steel core wire. One of the most popular acoustic guitar strings as used by the Eagles, Elvis Costello and Joe Bonamassa. Ernie Ball 80/20 bronze acoustic strings provide a crisp, bright sound with pleasing overtones. Available in Extra Light (10-50), Light (11-52), Medium Light (12-54), Medium (13-56), Rock and Blues (10-52), 12-String Light (9-46), and 12-String Medium (11-28).Now available in convenient three-set packs. 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 produce a bright, balanced sound with pleasing overtones. Gauges .012, .016, .024w, .032, .044, .054.