NEW CRYSTAL: New fibre for the core of the Corelli CRYSTAL strings, new computer-based technology and even more accurate automated tests during production have further enhanced the characteristics of the popular CRYSTAL strings ;Larger overtones, fast and more accurate response;quality sound projection from pianissimo to fortissimo;A Steel/Alu. wound with ball end ;Medium tension 7.5kg / 16.6lbs;Strong 6.7g / 14.8lbs;