CLASSIC GUITAR STRINGS SET XTC44 extra hard Spanish guitar string set with Pro Arte treble strings and Composite bass strings. Its 3 bass strings incorporate a special XT wound wound finished with anti-corrosion protection. Extra strong tension. Its state-of-the-art coating ensures a 4 times longer life in the use of this rope without sacrificing the classic touch and sound that characterizes the D'addario rope. They provide the musician with a longer life, better intonation and a better response in dynamics.