Elixir Phosphor Bronze strings begin with anti-rust plated plain steel strings that are corrosion resistant. They provide a clean feel and bright, vibrant tone. Both the steel core and its phosphor bronze winding are then treated with Elixir's patented Nanoweb thin polymer coating that completely envelops the entire string. This results in a long-lasting, rich tone with more audible high-frequency harmonics. The ultra-thin Nanoweb gives you the natural feel of untreated strings without sacrificing that important protection. This revolutionary product is a great value, as it means a dynamic and lively sound with less frequent string changes and fewer string purchases.