Ernie Ball Aluminum Bronze Extra Light Acoustic Set, .010 - .050 Patented technology brings a new voice to acoustic guitarists who seek a more expressive and dynamic string Aluminum Oxide provides a significant corrosion barrier, without coating the string Featuring Maraging Steel Hex cores, for greater low-end, and note separation Element Shield Packaging Prolongs string life and keeps strings as fresh as the day they were made Made in California, U.S.A. Featuring the finest and freshest materials.