D'Addario Phopshor Bronze Acoustic Guitar 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.   D'addario pays more to have their ball ends precision turned from solid brass stock. The edges have radii that prevent the ball end from cutting into wooden bridges or guitar tops. Each string is twisted to perfection right down to the three neatly wrapped "lock twists." And those lock twists help keep their plain steel strings from unraveling or breaking prematurely. Each and every spool of precision drawn high carbon steel wire D'addario uses goes through three quality control tests before it becomes a set of D'addario strings. Pioneering innovative string design has been a D'Addario family tradition for nine generations. Most guitar players don't realize that the inner core wire in ALL D'Addario steel strings is made from carefully drawn, hexagonally shaped, high carbon steel wire. The six "edges" of the core wire bite into the softer wrap wire, securing it all along its length. Environmental Package.   Gauges: .012; .016; .024; .032; .042; .053