CORROSION-RESISTANT, PRECISION WOUND – D’Addario Phosphor Bronze acoustic guitar strings are precision wound with phosphor bronze wrap wire, over a hexagonal high-carbon steel core WARM, BALANCED TONE - Phosphor Bronze wrap wire provides tried-and-true D’Addario acoustic tone, with beautiful balance and warmth suitable for all musical genres MOST POPULAR ACOUSTIC GUITAR STRING - Now the standard in acoustic guitar strings, Phosphor Bronze strings were originally pioneered by D’Addario in the 1970s EARN REWARD POINTS - D’Addario Phosphor Bronze acoustic guitar strings come with a code on the recyclable VCI bag, which you can register to earn Players Circle points MADE IN THE USA – Our Phosphor Bronze strings are made in the USA—drawn to exacting specifications at our New York production facility