Elixir strings are coated in a unique and patended way to protect wound strings from contaminants and corrosion. A flexible, strong, yet microthin polymer tube defends the string. This can be thought of as a heat shrink tube that's thinner than human hair. Nothing (including the coating) gets between the windings.
These Elixir Custom Light gauge Acoustic Guitar Strings have a Nanoweb coating which provides the balanced tone and a smooth response with the punch of non-coated strings.