D'addario EXL140 Nickel Wound, Light Top/Heavy Bottom, 10-52 Hybrid gauge combines EXL110 for flexibility with heavier 4th, 5th and 6th strings for a more solid low end Round wound with nickelplated steel for distinctive bright tone Environmentally friendly, corrosion resistant packaging for strings that are always fresh Made in the U.S.A. for the highest quality and performance String Gauges : Plain Steel .010, .013 .017, Nickel Wound .030, .042, .052