80/20 Bronze strings get their bright tone from their 80% copper and 20% tin components and are also commonly referred to as "brass" strings. 80/20 is the original acoustic string alloy selected by John D'Addario Sr. and John D'Angelico back in the 1930s. With less tin and more copper, these strings are popular for recording due to their crisp, deep and projecting tone. They also appeal to many traditionalists and vintage enthusiasts for their historical significance. 80/20's are wound on a hexagonally shaped, high carbon steel core, resulting in long lasting tone with excellent intonation. The EXP range feature D'Addario's patented life extending coating. A polymer coating is applied to the wrap wire BEFORE it is wound on a steel core, resulting in strings that sound and feel just like uncoated strings, while lasting at least four times longer.