Ernie Ball Coated 80/20 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 80 % copper & 20 % zinc wire, providing crisp pleasing overtones. Gauges .011 .015 .022w .030 .042 .052