Check the listing for details. EJ26 Custom Light Phos Bronze Acoustic Guitar Strings (11-52) 10. Condition: Open box. Listed at 74.99 USD. This convenient 10 pack saves you money! 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.