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. 80/20 Bronze produces a bright balanced sound with pleasing overtones. Earthwood Rock and Blues come with a plain G-string (no winding on the third string) similar to most electric string sets making it optimal for playing leads on acoustic guitar. Gauges .010 .013 .017 .030 .042 .052.