Thomastik-Infeld Spirocore cello strings are the technical further development of the rope-core strings because they have a more flexible spiral core made of steel. This spiral rope has a bigger elasticity, therefore a higher period of vibration than other rope strings. The sound is round, homogenous and powerful. Spirocore is supreme. These steel strings are the latest in Thomastik's technical knowledge. The Silver or Tungsten wound strings are among the most popular choices among professionals for their well known power.