From GHS:
Looking for piano-like tone and sustain? Choose Contact Core Super Steels.
Wound like a piano string, stainless steel wire is wrapped over a hex core, with an exposed section at the bridge section. This “exposed core” allows better contact, for a better transfer of sound vibration. The result is lower action, more definition, sustain, and vibrance with amazing intonation on the lower strings.
Unlock the full dynamic potential of your bass with Contact Core Super Steels!