Ernie Ball 80/20 bronze acoustic strings provide a crisp bright sound with pleasing overtones. Wound Strings are 80% copper 20% zinc wire wrapped around hex shaped tin plated steel core wire Plain strings are made of specially tempered tin plated high carbon steel The most popular acoustic guitar string alloy provides well balanced projection with crisp pleasing highs Element Shield Packaging Prolongs string life and keeps strings as fresh as the day they were made Made in California U.S.A. Featuring the finest and freshest materials.