From DAddario, the evolution of EXL, EXP, and NYXL and guitar strings, the coating string "XT is born. DAddario has worked on developing a long life string with unique coating technology and materials like NYSteel and FusionTwist which have been said to be difficult to achieve, combining natural tones and touch feelings like non-coated strings. The XT series has been coated with a high carbon steel core and plain strings, with a proprietary coating technology to ensure long life and a high performance string for strength, pitch stability and corrosion resistance.