XL Nickel-Wound, the most popular electric guitar strings from D'Addario, are precisely wound with nickel-coated steel around a carefully shaped hexagonal high-carbon steel core. The result is strings that deliver a durable, characteristic bright tone and excellent intonation, making them ideal for a variety of guitars and music styles. D'Addario offers a complete range of electric guitar strings for all your replacement or customization needs. .0559 gauge nickel-coated electric guitar string. Round wound with nickel-coated steel for a characteristic bright tone. Perfect as a replacement string or for creating custom sets. Made in the USA for the highest quality and performance.