ACOUSTIC GUITAR STRING SET String Sets Acoustic Guitar EJ Series Phosphor Bronze Light (012 - 016 - 024 - 032 - 042 - 053) - (Pack 3 sets). D Addario Phosphor Bronze acoustic guitar strings are recognized the world over for their superb, long-lasting tone. Phosphor Bronze was introduced for string making by D Addario in 1974 and has become synonymous with warmth, brilliance, and well-balanced acoustic tone. They are the most popular D Addario acoustic guitar strings.