XL Pure Nickel is our vintage electric string set, designed to embody the vibe of the ‘50s. In that early era of electric guitar, pure nickel was the main alloy used in electric guitar strings. Made with a high carbon steel core and pure nickel wrap wire, these electric strings revive the rich, clean tones heard in early blues, rock & roll, and country music. This 12-51 Jazz Light set adds some additional tension over Medium gauge Pure Nickel strings, for a slightly fuller tone.