Phosphor bronze was introduced by D'Addario into string manufacturing in 1974 and has since become synonymous with a warm, bright, and well-balanced acoustic sound. D'Addario's phosphor bronze strings are precisely wound with corrosion-resistant phosphor bronze around a carefully drawn, hexagonally shaped high-carbon steel core. The result is a durable, bright-sounding tone with excellent intonation. D'Addario offers a complete range of single strings for acoustic guitars to meet all your replacement or customization needs. 0.36 Gauge phosphor bronze wound acoustic guitar string. Preferred for its warm, bright, and well-balanced acoustic tone. Perfect as a replacement string or for creating custom sets. Made in the USA for the highest quality and performance.