Newtone Phosphor Bronze Master Class acoustic guitar strings use a phosphor bronze wrap on Newtone’s special round core wire. The phosphor bronze wrap wire will give you a warm, rich tone that lasts longer than 80/20 bronze. The round cores are part of Newtone’s vintage style string making method and help give Newtone’s strings greater string life and better playability than hex-core strings. Very important: Do not cut these wound strings to a desired length without first making a sharp bend into the string behind the cutting point or until the string is secured and tuned to pitch. Without either of these, the string will unravel.