D'Addario's lightest gauge of acoustic strings, EJ15s are ideal for beginners or any player that prefers a softer tone and easy bending. Phosphor Bronze was introduced to string making by D'Addario in 1974 and has become synonymous with warm, bright, and well balanced acoustic tone. D'Addario Phosphor Bronze strings are precision wound with corrosion resistant phosphor bronze onto a carefully drawn, hexagonally shaped, high carbon steel core. The result is long lasting, bright sounding tone with excellent intonation. D'Addario's lightest gauge acoustic guitar string set, known for its superb, long-lasting tone and playing ease Preferred for its warm, bright, and well balanced acoustic 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, .014, Phosphor Bronze Wound .023, .030, .039, .047