Ernie Ball Slinky Flat Wound Bass Strings combine the smooth feel of traditional flats and the power of Cobalt. Featuring a Superbright Cobalt ribbon wrap, Cobalt under wraps and optimal hex-core to wrap ratio, the new Flat Wound Bass strings are the first flat that actually feels like a flat and sounds like a round. Gauges: 0.055, 0.075, 0.090, 0.110.