D'Addario PB045 Phosphor Bronze Single Acoustic String Single

Gauge: .045.
Genuine phosphor bronze alloy retains flexibility as well as brilliant tone for many hours of hard play. The PB045 string has a computer-controlled wrapping around a hex core that ensures consistency and extends life. Many top guitarists won't play any other brand.
D'Addario is the world's largest manufacturer of strings for musical instruments. Regardless of your playing style, D'Addario has a set that's right for you.