DAddario EXPs deliver the most natural-sounding, longest-lasting coated strings available. Through our advanced EXP Coated Technology, we have perfected the art and science of coated string-making to deliver extended play strings that sound identical to our world famous XLs. Plus, weve dramatically improved the corrosion resistance, longevity and durability of plain steel strings through an exclusive compound tin-plating process. Finally...coated electric strings that deliver longer life, completely natural tone and the feel of uncoated strings. You wont believe they are coated!