STRING SET FOR ELECTRIC GUITAR String Set for Electric Guitar XL Series Nickel Wound Heavy (12 - 16 - 20 without bordon - 32- 42 - 54): perfect for altered tunings to Eb or Re. D'Addario XL strings for Electric Guitar 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 a distinctive, brilliant tone and excellent intonation.