XL Nickel Wound electric guitar strings are the standard against which all other strings are measured. D’Addario’s best-belling electric set, XL Nickel has been revered by players everywhere since 1974. Made with a high carbon steel core and nickel-plated steel wrap wire, XL Nickel strings have a bright, versatile tone, ideal for a wide variety of musical styles. 11-52 Medium Top/Heavy Bottom gauge strings are a hybrid, providing the high strings moderate flexibility, with a booming, tight low-end.