Experience acoustic brilliance with the Ernie Ball Earthwood Phosphor Bronze Alloy Acoustic Guitar strings. These strings are made from a blend of copper, tin, and phosphorus, wrapped around a tin-plated hex-shaped steel core wire for better sonic performance. It produces a clear mellow, ringing sound to enhance the tonal depth of your guitar. | Ernie Ball Earthwood 0.011 - 0.052 Phosphor Bronze Alloy Acoustic Guitar String (P02148)