D'Addario H514-44H cello string C-4 4/4, heavy, tungsten/silverD'Addario H514 44H cello string C 4 4 4, heavy, tungsten silver Multi Strand twisted steel core strings are superb for the advanced and professional players. The small string diameter provides quick bow response. Through special manufacturing techniques, the Helicore strings have a warm, clear sound with excellent pitch stability and longevity.