D'Addario's most popular set for acoustic basses, the EPBB170, offers a rich, deep, and penetrating sound. Phosphor bronze was introduced by D'Addario into string manufacturing in 1974 and has since become synonymous with warm, bright, and balanced acoustic tone. D'Addario phosphor bronze strings are precisely wound with corrosion-resistant phosphor bronze around a carefully shaped, hexagonally drawn high-carbon steel core. The result is a durable, bright-sounding tone with excellent intonation. Specifically designed for use on all 4-string acoustic basses, it is favored for its warm, bright, and balanced acoustic sound. Environmentally friendly, corrosion-resistant packaging ensures that the strings remain fresh. Made in the USA for the highest quality and performance. String gauges: Phosphor bronze wound .045, .065, .080, .100.