Bright, balanced tone with excellent projection and clarity Extra Light gauge is ideal for players who want less string tension for easier play across the fretboard Wound Strings are 80% copper, 20% zinc wire wrapped around high-carbon steel core wire Element Shield Packaging prolongs string life and keeps strings as fresh as the day they were made Made in California, USA with the freshest and finest materials 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 .010, .014 .020, .028, .040, .050.