The Ernie Ball Earthwood 12-String Light Phosphor Bronze Acoustic Guitar Strings are made from 92 percent copper, 7.7 percent tin, 0.3 percent 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.