ELECTRIC GUITAR STRING SET String Set for XL Series Nickel Wound Electric Guitar, Medium Top / Heavy Bottom (011 - 014 - 018 - 030 - 042 - 052). D'Addario XL Electric Guitar Strings have been recognized worldwide as '' The Guitarist's Choice '' among guitarists of all genres and styles. XL strings are wound with great precision with nickel plated steel onto a hexagonal shaped core, resulting in strings with distinctive, brilliant tone and excellent intonation.