The Nexus Polymer Coated Bass Strings from Rotosound feature a black polymer coating over a Type 52 wrap to create high-energy bass strings with rich mid-tones. Gauges: 45-65-85-105 Order the NXBL130 (sold separately) to add an extra low B string and make this a 5-string set. An alternative to steels with high presence Silky smooth black polycoat dressing over a Type 52 wrap Extended playing life