Strings for electric guitar. D'Addario XL ProSteels utilize an exclusive corrosion-resistant steel alloy that delivers super-bright tone without shrill overtones. They offer a palette of harmonically rich, brilliantly penetrating highs combined with pronounced, tight-and-tough lows. Medium gauge. Unique highly magnetic steel alloy offers brighter, crunchier tone and increased sustain. Gauges: . 011, . 015, . 019, . 028, . 037, . 050