EXL117 is an extreme hybrid set, optimally designed for tuning guitars down a whole step to D, while maintaining a comfortable playing tension like that of a "light" gauge set. The XL Nickel Wound strings are D'Addario's most popular electric guitar strings, precision wound with nickelplated steel onto a carefully drawn, hexagonally shaped, high carbon steel core. The EXL117 nickel wound strings are long lasting and ideal for the widest variety of guitars and musical styles, with distinctive bright tone and excellent intonation.