D'Addario Flat Tops are round wound, then precision ground, leaving the outer surface smooth and "semi-flat". This produces a smooth, flattened playing surface, but does not sacrifice the superb tone and sustain associated with phosphor bronze strings. Flat Tops greatly reduce finger noise and are excellent for recording and flat-picking. String Gauges: Plain Steel .013, .017, Phosphor Bronze Wound .026, .035, .045, .056