Thomastik Spirocore S42 Double Bass Strings are THE classic jazz double bass string. Constructed with a flexible multi-wire spiral steel core, Spirocores have a greater elasticity than that of conventional strings, which means less inertia and a higher propensity to musical vibration (think growly). The sound is full and homogenous, balanced and voluminous. They are highly responsive, long lasting strings that are legendary for their great sustain, distinctive tone, and playability. Although Spirocores are best known as a pizzicato or jazz string, they are labelled a hybrid set. When bowed, the tone is bright but leaves little room for error. We’ve heard Spirocores being described as unbowable, but they were the string choice for the bass section of the Vienna Symphony for many years, so we’ll leave that to you to decide.