D'Addario Helicore Octave Violin String SetThe Helicore Octave Violin set is designed to be played one octave below traditional tuning for a new world of tonal and stylistic possibilities. It utilizes the same core technologies as the original violin set for quick bow response, comfortable playability, and clear sound. Instrument: Violin (Octave) String Type: Set Size: 4 4 Gauge: Medium E String: Aluminum wound over a steel core, Removeable Ball End A String: Silver wound over a steel core D