Ernie Ball Everlast Coated acoustic guitar strings use groundbreaking nanotechnology that repels unwanted moisture and oils that negatively impact your tone. Our proprietary treatment is applied to both the inner hex core and outer wrap wire to provide ultimate protection without compromising tone or feel. Made from 80% copper, 20% zinc wire wrapped around hex shaped brass plated steel core wire providing a crisp, ringing sound with pleasing overtones. Gauges .010, .014, .020, .028, .040, .050