D'Addario EXPPBB170 Phosphor Bronze Coated Acoustic Bass Strings, Long Scale, 45-100 Designed specifically for use on all 4-String acoustic basses EXP Coated phosphor bronze for warm, bright, well balanced acoustic tone and 4 times more life Corrosion resistant packaging for strings that are always fresh Made in the U.S.A. for the highest quality and performance String Gauges: Phosphor Bronze Wound .045 .065, .080, .100