STRINGS SET FOR ACOUSTIC GUITAR String Sets Acoustic Guitar Series EJ Phosphos Bronze Extra-Light (010 - 014 - 023 - 030 - 039 - 047) - (Pack 3 games). D'Addario Phosphor Bronze strings for acoustic guitar are recognized all over the world for their magnificent and lasting tone. The Phosphor Bronze was introduced for the manufacture of strings by D'Addario in 1974 and has become synonymous with warmth, brilliance and good balanced acoustic tone. They are D'Addario's most popular acoustic guitar strings.