Ernie Ball Earthwood Phosphor Bronze 12-String 9-46 Acoustic Guitar Strings Ernie Ball Earthwood acoustic guitar strings are crafted with an exclusive phosphor bronze wrap wire, made from 92% copper, 7.7% tin, and 0.3% phosphorus. These strings cater to the demands of acoustic musicians worldwide, delivering deep, rich bass notes with clear, bright trebles. Ernie Ball Slinky Acoustics are trusted by renowned artists such as The Counting Crows, The Edge, and Maroon 5. Each set of strings is made using the finest and freshest raw materials and sealed to ensure they remain as fresh as the day they were made.