MADE IN THE USA! Nickel Wound Electric Guitar Strings 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. Gauges: .013 .017 .026 .036 .046 .056.