D'Addario XL Nickel Wound Electric Guitar strings are world-renowned as "The Player's Choice" amongst players of all genres and styles. XL's are precision wound with nickelplated steel on a hex-shaped core, resulting in strings with a distinctive bright tone and excellent intonation. This High-Strung Nashville Tuning gauge basically uses the octave strings from a 12-string set to give you a 12-string sound out of your 6-string guitar.