These Cobalt Slinky Bass Strings from Ernie Ball are intended for use with 5-string electric basses and feature a proprietary iron-cobalt alloy wrap wire over a tin-plated high-carbon steel hex core wire. This proprietary cobalt alloy provides a stronger magnetic relationship between your strings and your pickups when compared to other alloys used for making strings. As such, they help facilitate an increased output level with a wider dynamic range than other Ernie Ball strings, as well as a boosted low end, clear and crisp highs, and an enhanced overall harmonic response. This 5-string set is gauged .045 - .130.