D'Addario's premium uncoated acoustic string set that provides a crisp and clear sound to accentuate the unique tone of your guitar. NB13556BT delivers the ideal balance of volume, projection and comfortable playability - with string tension balanced across all six strings. 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. Nickel Bronze delivers unrivaled clarity, resonance and projection, as well as outstanding balance and harmonically rich overtones. Players will also enjoy improved tuning stability and higher break resistance, thanks to D'Addario-engineered NY Steel cores and plain steel strings. String Gauges: Plain Steel .0135, .018, Nickel Bronze Wound .024, .032, .042, .056.