D'Addario XT 9-42 Electric Guitar StringsStand the test of time with strings that endure. D'Addario XT Electric Nickel Plated Steel strings combine D'Addario's strongest high carbon steel with an advanced corrosion resistance treatment on every string in the set, giving you enhanced break resistance and unyielding pitch stabilityall while preserving the tone and feel of your favourite uncoated strings. These strings are made to stay, with uncompromising performance that never fades away.