Originally introduced in the 1930s, 80/20 Bronze is known for its crisp, bright, and projecting tone that appeals to many traditionalists and vintage enthusiasts. All D’Addario acoustic strings are precision wound on a hexagonally shaped, high carbon steel core, resulting in long lasting, bright sounding tone with excellent intonation. • D'Addario's heaviest 80/20 bronze set, ideal for heavy strumming and flatpicking • Extra-bright tone mixed with deep and projecting bottom end • String Gauges; Plain steel .012, .017, Nickel Wound .026, .035, .045, .056 • Corrosion resistant packaging for fresh strings, always! • Made in the U.S.A. for the highest quality and performance