D'Addario offers 3 sets of strings in one convenient, cost-effective & environmentally friendly multipack. Each set is packaged in separate VCI bags for corrosion resistance, so they're fresh when you're ready to restring. Phosphor Bronze was introduced to string making by D'Addario in 1974 and has become synonymous with warm, bright, and well balanced acoustic tone. D'Addario Phosphor Bronze strings are precision wound with corrosion resistant phosphor bronze onto a carefully drawn, hexagonally shaped, high carbon steel core. The result is long lasting, bright sounding tone with excellent intonation. DAddario Phosphor Bronze acoustic guitar strings are precision wound with phosphor bronze wrap wire, over a hexagonal high-carbon steel core. Phosphor Bronze wrap wire provides tried-and-true DAddario acoustic tone, with beautiful balance and warmth suitable for all musical genres. Now the standard in acoustic guitar strings, Phosphor Bronze strings were originally pioneered by DAddario in the 1970s. DAddario Phosphor Bronze acoustic guitar strings come with a code on the recyclable VCI bag, which you can register to earn Players Circle points. Our Phosphor Bronze strings are made in the USAdrawn to exacting specifications at our New York production facility.