D'Addario EFT17 Flat Top Phosphor Bronze Acoustic Guitar Strings - Medium Flat Tops greatly reduce finger noise and are excellent for recording and flatpicking. They 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. String Gauges: Plain Steel .013, .017, Phosphor Bronze Wound .026, .035, .045, .056