Description Ernie Ball Earthwood Phosphor Bronze Medium 12-54 Acoustic Guitar String Set 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, .016, .024w, .032, .044, .054 “These are the bronziest ones. Wait. What?  Ohhh they are also the most phosphoriest ones too!”      –  Matty Connolly of The Axe Palace