Extended-life, coated steel strings.
Through advanced EXP Coated Technology, D'Addario has perfected the art and science of coated guitar strings to deliver extended-play replacement strings that sound identical to the renowned D'Addario XL series. A micro-fine layer of concentric EXP coating is applied to the wrap wire prior to winding, resulting in guitar strings that deliver longer life, completely natural tone, and the feel of uncoated strings. Plus, the whole set lasts 4 times longer thanks to D'Addario's exclusive compound-plated, plain steel strings, which offer maximum corrosion resistance. You won't believe they're coated. The EXP140 guitar string set comes with a free extra first string.