From Elixir:

The longest lasting tone night after night!

Elixir^® Strings Acoustic Phosphor Bronze with NANOWEB^® Coating deliver distinctive phosphor bronze warmth and sparkle together with extended tone life.

• Only coated string brand to protect the entire string with an ultra-thin coating, keeping gunk out of the gaps between the windings
• Extended Tone Life – players report their tone lasts longer than any other string, uncoated or coated
• Consistent performance and tone – ready to play whenever you are
• Smooth feel that is easy on your fingers and enhances playability
• Reduces finger squeak – good for both performance and recording
• Anti-Rust Plated Plain Steel Strings resist tone-deadening corrosion, ensuring a longer life for entire set
• With less hassle and expense of frequent string changes, spend more time making music