A micro-layer of EXP coating is glued onto the phosphor bronze wire which is then wound onto the central wire in a hexagon shape. The result is a built-in barrier against corrosion and wear that can quickly sap the life of your strings and your tone. EXP strings have a natural Round Wound feel and extra-bright tone that lasts three to four times longer than traditional guitar strings. Coupled with our compound plated steels, EXPs are the most durable and natural coated strings you can buy!