Ernie Ball Everlast Coated acoustic guitar strings use ground-breaking nanotechnology that repels unwanted moisture and oils that negatively impact your tone. Made from 92 percent copper, 7.7 percent tin, 0.5 percent phosphorus wire wrapped around brass plated hex shaped steel core wire, Phosphor Bronze strings produce warm rich bass tones with clear bright trebles. Gauges .013, .017, .026, .034, .046, .056.