D’Addario Phosphor Bust Acoustic Guitar strings are acclaimed worldwide for their fantastic, long-lasting tone. Phosphor Bust was introduced to thread making by D’Addario in 1974 and has become synonymous with warm acoustic tone. This High-Strung Nashville Tuning set utilizes the octave strings from a 12-thread set to give your 6-thread guitar a 12-thread sound.One set of strings gauges .010-.027.