Thundergut is a special very dense and elastic-plastic blend developed at Aquila headquarters which grants better performances than common polyurethane and silicon rubber strings. * Thundergut ensures quick and stable intonation. * Thundergut strings do not present excessive stretching during tuning. * Thundergut string surface is not particulary sticky, as is silicone rubber. These strings are not too slippery when touched and are not so easy to turn on itself when pressed on the keyboard as in the case of polyurethane strings. * Made in Italy.