D'Addario Phopshor Bronze Acoustic Bass strings are acclaimed worldwide for their great - long-lasting tone. Phosphor Bronze was introduced to string making by D'Addario in 1974 and has become synonymous with warm acoustic tone. PBB130 is a .130 gauge phosphor bronze bass guitar string. Perfect for adding a 5th string to the EPBB170 4-string set. 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.