Thomastik Superflexible steel core strings for universal use. This strings are an advance over conventional solid strings, lying midway in the path of evolution from the solid core to the advanced spiral core type. The solid core has been replaced by a cable-type structure made up of braided steel threads. This reduces the stringâ€™s stiffness, improving its elasticity. Superflexible is incomparably responsive and its tone seems to literally radiate from the instrument, without the least harshness. Durability, tuning stability and purity of open fifths are unsurpassed.