Ernie Ball Earthwood Phosphor Bronze Acoustic Guitar Strings are made from 92% copper, 7.7% tin, 0.3% phosphorus wire wrapped around tin plated hex shaped steel core wire. These guitar strings have a light orange, gold color and provide a mellow, ringing sound, with excellent clarity. Gauges .012.5, .016.5 .024w, .034, .046, .056.