D Addario Electric Guitar Strings 11-49 EXL115 Blues/Jazz Rock. DAddario pioneered the use of nickel plated steel for electric guitar. Today, discerning professionals like Mark Tremonti, John Scofield, Pat Metheny, and Brad Delson, just to name a few, choose XLs for their distinctive bright sound and excellent intonation. Gauge 11,14,18,28,38,49 XL strings are wound with nickel plated steel Well known for their distinctive bright tone Excellent intonation.