Check the listing for details. D'Addario EJ39 12-String Phosphor Bronze Medium 12-52 Acoustic Guitar Strings. Condition: New. Listed at 12.94 USD. D'Addario EJ39 12-String Phosphor Bronze Medium 12-52 EJ39, D'Addario's medium gauge 12-string acoustic guitar set provides heavier tension resulting in a bolder, more resonant acoustic tone with higher resistance for heavy strumming or aggressive fingerpicking.Medium gauge 12-string set, ideal for heavy strumming and a resonant, projecting tonePreferred for its warm, bright, and well balanced acoustic toneEnvironmentally friendly, corrosion resistant packaging for strings that are always freshMade in the U.S.A. for the highest quality and performanceString Gauges: Plain Steel .012/.12, .016/.016, Phosphor Bronze Wound .025/.010(p), .032/.014(p), .042/.020(p), .052/.030(w)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.