Ernie Ball Slinky Flatwound Bass Strings combine the smooth feel of traditional flats and the power of Cobalt. Featuring a SuperBright Cobalt ribbon wrap, Cobalt underwraps and optimal hex-core to wrap ratio, the new Flatwound bass strings are the first flat that actually feels like a flat and sounds like a round. Gauges .045, .065, .080, .100 .130