D'Addario NB1256 Nickel Bronze Acoustic Guitar Strings - Light Top/Med Bottom 12-56 Nickel Bronze strings are the premium uncoated acoustic strings by D?Addario. Featuring an innovative combination of nickel-plated phosphor bronze wrapped onto a high carbon NY steel core, these strings bring out the unique tonal characteristics of any guitar, allowing its natural voice to truly shine. NB1256 combines medium gauge bottom strings for increased resonance and volume with light gauge top strings for more comfortable playability and single note bending. String Gauges: Plain Steel .012, .016, Nickel Bronze Wound .025, .035, .045, .056