Made from 80% copper, 20% zinc wire wrapped around hex shaped tin 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. .012, .016, .024w, .032, .044, .054. Part number 2003