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 colour and provide a mellow, ringing sound, with excellent clarity. Gauges .009 .009, .012 .012, .020w .009, .026 .012, .036 .020p, .046 .026