BASS STRING SET XL Series Round Wound Bright Bass Strings, Medium, Long Scale (020 - 032 - 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 on a hexagonal core, resulting in strings with a distinctive, brilliant tone and excellent intonation.