Spiro core strings are a further technical development of our Kunstler Sail series and have a flexible spiral steel core. This core has greater elasticity than that of conventional strings, which means less inertia and a higher propensity to musical vibration. The sound is full and homogenous, balanced and voluminous. The string has been calibrated to satisfy the express wish of many artists for an equally effective arco and pizzicato. Particularly bassists with a low C extension will value this strings reliability. Spiro core is also much favored by jazz bassists because of its suitability for amplified pickup tone. Thomastik-Infeld has tackled notorious cello problems such as wolf notes and muting difficulties with Spiro core C and G strings in wound tungsten and silver wound. Spiro cores hi-tech core makes for effortless fingering, responsive bowing, stable tuning and a very long string life. With Spiro core the steel strings technical possibilities have been developed to their maximum.