Ernie Ball Extra Slinky Flatwound Electric Bass Strings - 40-95 Gauge. Ernie Ball Slinky Flatwound Bass Strings combine the smooth feel of traditional flats with the modern power of cobalt. Featuring a super bright cobalt ribbon wrap, Ernie Ball’s optimal core to wrap ratios deliver an innovative new bass string that features the tonal qualities of a round wound with the silky smooth feel and fundamentals of a flatwound string. Enhanced lows, focused mids, and crisp highs, Round wound sound, Less finger noise, Finest and freshest raw materials.