An ultra-fine layer of EXP Coating is bonded to the phosphor bronze wrap wire which is then wound onto a NY High Carbon Steel core hex-shaped core wire. The result is a built-in barrier against the corrosion and wear that can quickly sap the life out of your strings and your sound. Sweetwater knows that choosing the perfect string is vital to a musician’s sound. EXP coated phosphor bronze strings have a natural feel and sound warm and bright with a new-string tone that lasts three to four times longer than traditional guitar strings.