Now available in convenient three-set packs Ernie Ball earth wood 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. 011, . 015, . 022W, . 030, . 042, . 052.