Ernie Ball Coated Phosphor Acoustic Guitar Strings feature a proprietary enamel coating on the wound strings, and a rust-resistant plating on the plain strings. In addition to the exclusive coating, all plain strings are reinforced with a patented winding of titanium wire around the lock twist of the ball end. The wound strings are wrapped with an alloy combination of 92 % copper, & 7.7 % zinc wire, and .3 % Phosphor providing excellent clarity with rich warm overtones. The Eagles, John Mayer, and Chris Cornell are just a few of the many musicians who play these strings both live and in the studio. Made with the finest and freshest raw materials, all Ernie Ball strings are hermetically sealed to ensure your strings stay as fresh as the day they were made.