"EHR320's combine the universal playability of a traditional 9-42 set with the benefits of an exclusive ""Half Round"" manufacturing process.- D'Addario's popular extra-light gauging with an exclusive semi-flat surface- Centerless ground stainless steel delivers round wound tension with a flatwound feel- 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 .009, .011, .016, Stainless Steel .024, .032, .042- Environmentally friendly, corrosion resistant packaging for strings that are always fresh"