These strings are fitted as standard on the Sonic Violin range unless specified otherwise. Helicores are very popular multi stranded steel cored strings. They give a very clear sound, stable pitch and are especially durable. They also represent good value compared to similar specification strings. These heavy tension strings work well on mid range instruments and will produce a louder sound than the medium set. I also upgrade the set with the very popular Kaplan "non whistling" wound E string.